


Unorthodox

by Anonymous



Category: Dr. STONE (Anime), Dr. STONE (Manga)
Genre: Age Regression/De-Aging, Alternate Universe - Modern Setting, Crossplay, Date Rape Drug/Roofies, Discord: The Kingdom of Shipping (Dr. STONE), Drugged Sex, Drunk Sex, Eventual Caregiver Relationship, Gender transformation, Inspired by Roleplay/Roleplay Adaptation, Light Bondage, M/M, Science Experiments, Senku with a vag :), Sex Change, Somnophilia, TKSRoleplayCollab, TKSRoleplayCollabsEventSep2020, TKSevents, TheKingdomofShipping, Underage Sex, age gap, dubcon, genetic experiments, infantilization, noncon
Language: English
Status: Completed
Published: 2020-09-17
Updated: 2020-10-03
Packaged: 2021-03-08 01:55:27
Rating: Explicit
Warnings: Underage
Chapters: 9
Words: 70,564
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26507836
Author URL: https://archiveofourown.org/
Summary: When Xeno finds a strange abandoned experiment in the back of the NASA labs, he decides the best course of action is to use his intern, Senku, as an unknowing specimen. The results on Senku's body is astonishing, but when Xeno attempts to push the experiment even further, Senku finds that he is no longer having to deal with different genitalia... but his body has regressed back to his early teenage years.The true problem, however, lies in the fact that Xeno cannot seem to keep his hands off Senku's new body...
Relationships: Ishigami Senkuu/Dr. Xeno, Ishigami Senkuu/Stanley Snyder
Comments: 2
Kudos: 57
Collections: Anonymous, TKS RP and Gen Ships Month - September 2020





	1. Experiment 01

**Author's Note:**

> Hello!  
> This is an RP adapted into a story~
> 
> :) we hope you enjoy!

* * *

Xeno had never seen the compound before. 

It wasn't uncommon for many of the scientists around the lab to leave their unfinished projects behind. It also wasn't too uncommon for the scientists around NASA to have their own areas of interest, using grants and such from NASA to fund projects of their own, some of the experiments never having anything to do with space exploration. 

So Xeno wasn't too shocked when he came across the old and battered box in one of NASA's many storage rooms. He was simply storing away some of his own most recent journals and such, a task he could give to his assistant, but Xeno enjoyed knowing where everything was for easy retrieval. The box that caught his eye wasn't anything special, no markings on it that should have called for closer inspection. But it's placement was rather odd, tucked so far behind other boxes and shelves that it took a lot of pushing and pulling of equipment to get to it. Inside were a few small sealed darkened-glass containers, as well as an old journal. No name to be seen. 

Xeno carried the box out with him, returning to his office as he looked over the browned glass bottles. Inside was a thick liquid. He spun it slowly, unsure if it was a serum or tincture - such things must be handled differently, you see. Rough shaking could cause whatever compound it was to separate or destroy itself. 

It was very early in the morning as Xeno sat at his desk, no one having come in just yet. Xeno was always ungodly early, but he enjoyed the silence. He placed the dark bottles on his desk - there were two total, as well as the journal. Going through other's journals in an academic place was normal. If you didn't want your stuff studied then it was best to store it at home. By keeping it here, whoever wrote this was leaving it for someone else to find.

But, as Xeno read through the scribbles on the pages, his brows furrowed. Such a strange compound this person had made. The ingredients weren't too far from unusual, but they were rare for sure. Not only that, but the procedure to make it was absolutely wild, something that would have taken months of work only to produce a small amount of the liquid that sat in the bottles. Red text was scribbled in places, correcting measurements or chemicals, or tips such as  _ 'serum is gelatinous, but dissolves in warm water. No taste or smell detected.' _ A few other notes called out to Xeno. Mainly, one near the end, in bold letters:  **End results were astonishing but... undesirable. Will need further research! There must be a way to reverse the effects!**

Xeno arched an eyebrow slowly. It was an area of science that he did not have too much experience in, but the journal made one thing clear: this was some sort of genetic experiment. A forced body mutation. But the results were only 'undesirable'. And there were no reports of anyone growing extra limbs or similar over the years. But Xeno couldn't help but wonder what the results were, exactly. It would be possible to alter the compound, with the right equipment... but he needed to see what the current outcome would be. And any scientist would know how silly it was to run self experiments... 

It would be easier to ask, yes. But Xeno's assistant was a smart boy. He also knew better than to willingly volunteer for drinking a strange liquid found in the back storage rooms at a NASA facility. None of the ingredients in the compound were inherently dangerous. A small bit would not hurt him. And Xeno was much more experienced than the boy - if any unwanted side effects happened then they would need Xeno to be lucid and able to help. So Senku was the best person to drink it.

The notes were right - the serum was quite thick, like gelatin, but dissolved nicely in a cup of hot coffee. Xeno even added a bit of sugar, just for taste. It didn't smell strange at all. Nothing in the notes mentioned how much of the serum one needed to drink to see a change, but hopefully this would be enough. They had more, for future experiments. People were just now coming into the offices, which meant Senku wouldn't be too far behind. Xeno placed the cup of coffee on his assistant's desk, which sat adjacent to his own. He sat then, sipping his own untainted coffee, not being able to help the small grin that formed on his lips. What sort of changes would happen?

* * *

Senku really couldn’t complain. An acceptance to San Francisco State, a merit scholarship, and an internship at NASA’s Ames Research Center, every piece of his childhood plan was falling into place. Sure his English was a little rusty, and the commute from San Francisco to Mountain View was a little long for his liking, but everything was worth it to achieve his goals. 

His schedule allowed him to spend all day at the research center every Friday, meaning he had to leave as early as possible to get the most out of it. The train ride was two hours, meaning he had to catch the 6am train, but at least he had plenty of time to review the summaries his mentor had sent him throughout the week. 

In Senku’s opinion, his mentor was the best part of his time spent in America, aside from his aforementioned goal-achieving. Dr. Xeno was just strict enough that Senku had structure, he always had tasks to make sure his assistant was never bored, and he was kind enough that Senku didn’t resent him for his constant workflow. Every Friday morning he would walk in, crimson eyes sparkling, eager to get started on whatever Dr. Xeno had planned that day.

When the train finally pulled up to the station, Senku immediately rushed out of it and towards the research center. He knew Dr. Xeno was already there, and he didn’t want to waste a moment of his mentor’s time. He noted the time as he arrived:  _ 8 hours, 24 minutes, 37 seconds.  _

He slowed down when he neared Dr. Xeno’s office, carefully opening the door and smiling when he saw his mentor seated at his desk, seeming to have not started on any work yet, thankfully.

“Good morning, sorry I’m late.” Senku gave a quick habitual bow, hanging his bag and coat on a hook, and taking his usual seat by the doctor’s desk. He smiled at the still-hot cup of coffee in his workspace, and took a grateful sip. He hadn’t had time to make his own that morning. He normally didn’t take his coffee with sugar, but he didn’t want to seem ungrateful. “Thank you for this, I hope I didn’t keep you waiting too long?”

  
  


Xeno's smile was warm. Senku had taken the coffee so thankfully. But that's how Senku always was, so eager to take anything from Xeno with so much enthusiasm. It made Xeno wonder if Senku would have gone under experimentation if he had asked properly. Perhaps if he had done it with some praise snuck in. Such a good assistant, more like an apprentice than anything. Most others in the offices treated interns and assistants as just that, someone to do the grunt work. But Senku's mind was far too great for that. 

"You didn't keep me waiting," Xeno said, keeping his smile. He knew all too well how far the poor boy had to travel during these early mornings. "I was busying myself, reading some... new material," he said it as he placed the old and tattered journal among his other books and files. No need for Senku to see that, at least not yet. "There are some things I wish you to go over this morning," Xeno started then, their usual talks, Xeno setting out Senku's daily schedule. It was a rather simple day, all things considering. Usually daily tasks would have them wandering about the NASA center, a thing Senku always seemed to enjoy, but the day was mostly boring (though very important) paperwork. 

Which was a good thing. It allowed Xeno to carefully watch his assistant, a small notepad near him, ready to jot down any concerning changes. For now, there was nothing to note at all. Senku seemed relatively normal. Perhaps it wasn't enough? Or, perhaps it took some time to affect the body. Xeno was prepared for either outcome, letting the morning go on as usual, occasionally speaking to Senku when questions or comments would pop up.

Senku nodded as he listened intently to Dr. Xeno’s schedule for the day, quickly jotting down his schedule in his notebook. He had to admit he was a little disappointed in the day’s tasks, but he supposed that so much paperwork came with the profession. He nodded once Dr. Xeno was done explaining the day, and immediately set to work. 

As he pored over the first packet of paperwork, Senku continued to take small sips of his coffee. He couldn’t help but notice Xeno’s demeanor, seeming to watch him more often, more intently. Scribbling down some notes every few minutes or so. He shrugged it off, though, keeping his own attention on the papers in front of him. 

By the time he finished the first chart, Senku had drank his full cup of coffee. He pushed the mug to the side, turning his attention back to the computer in front of him. The only sound in the room was the clacking of keys, and Xeno’s occasional scratches on his notepad.

An hour or so later, Senku felt a dull pain in his stomach. Maybe the coffee was disagreeing with him, or the breakfast sandwich he had bought at the train station. He let out a soft sigh, standing up and stretching out. “I’m going to run to the restroom, is that alright?” Once his mentor had given him the okay, Senku made his way down the hall to the restroom. 

Xeno’s assistant had left so quickly to the restroom! Xeno was sure to note this down. It would be quite unsatisfactory if the results of the serum were simply an upset stomach or digestive upset. Coffee had never seemed to both Senku before, so unless he had a small flu or had eaten something else, then the cause had to be what Xeno added to his coffee. 

Senku’s pain had only gotten worse as the seconds passed, spreading throughout his lower body. Once he opened his pants, he finally understood what had gone wrong. 

Immediately he redressed himself, rushing back to the office. He quickly closed the door behind him, and stared over at Dr. Xeno. “Um… Doctor? I’m having a bit of an… issue.”

When Senku returned, Xeno was quick to note the look of worry on his face. It was slight, perhaps Senku had worked hard to hide it as he walked back through the halls towards his office. But his words confirmed one thing: something had changed. Something, upon looking Senku up and down, must have happened either internally, or at least beneath his clothing. Xeno stood from his desk then, turning to face his assistant, his hand beneath his chin as he gave a curious stare. He needed to play dumb, just for a little while longer. "Are you feeling okay, Senku?"

It was important to know - Xeno stepped closer, placing the back of his palm against Senku's forehead. A bit warm, perhaps a slight fever. His own brows began to furrow, hopefully this serum didn't have any adverse side effects that required an emergency room visit. "Perhaps you should sit down."

Senku didn’t miss the doctor’s intrigued look as he turned around, though it was far from important to him at the moment. “I… um…” His face flushed red as he thought of what to say, thankful at the time bought by Xeno taking his temperature. 

He quickly took the doctor’s offer of a seat, tapping his foot as he thought. He didn’t want to be too forward about it, but he also didn’t want to be crass. Should he say it in Japanese, in case he said the wrong thing in English? Was Dr. Xeno’s Japanese advanced enough for that?

Finally he pursed his lips and took a deep breath, letting it out in a sigh. He pinched his forehead to both cover his embarrassment, and to keep from meeting Dr. Xeno’s eyes. “I… I don’t know how it happened, but…” His voice lowered to a mumble and seemed to jump an octave, and he spoke fast enough that it was almost incomprehensible. “ _ Myprivatepartsaregone… _ ”

Senku was embarrassed. That alone spoke enough on what could have happened. Xeno did his best not to let his expression seem intrigued as Senku worked through his thoughts, but it became hard to keep up the act once Senku finally revealed what was troubling him. Thankfully Senku's gaze was turned down and unable to see the quick smirk that tugged at Xeno's lips, a smirk he forced away as he cleared his throat. No wonder the previous scientist had noted that the effects were enough to warrant looking into a way to reverse them... But, something plagued Xeno... 

"When you say gone..." Xeno sat in his own chair now, though rolled it to be closer to Senku, their knees nearly touching as he folded his hands together, "one's genitals don't just vanish, Senku. Surely, you must mean something else." This was quickly entering a territory that Xeno had not prepared himself for, but he was equipped to deal with it all the same. He never did deny it to himself, the thoughts of slowly drawing Senku into the comfort of being touched, caressed, perhaps even more. But Xeno kept such thoughts at bay - he was this boy's teacher, in a way. Even now, Xeno did his best to keep his thoughts purely academical. This was for research, after all.

Senku held tightly to the chair, staring down at his own lap and refusing to meet Dr. Xeno’s eyes. “I… I didn’t see anything else, but… I didn’t check.” He kept his thighs tight together, the blush spreading further to his ears.

_ What the hell had happened? _ Today had seemed so normal, there was nothing different that he had done… This all seemed so strange to talk to his mentor about, and while the man was a doctor, he tended to work with rockets rather than human bodies.

“I… um… I don’t remember doing anything that might have done this, but…” he sighed, closing his eyes. “I can just go visit the campus health center or something when I get back. I don’t want this to distract from our work, it’s far less important.”

With that, Senku let his chair swivel back around, and he tried to focus on his next task, and not on the stare Dr. Xeno was giving him.

_ Oh _ . Xeno couldn't help the smile now. "We can't have that. I don't think such measures are necessary." Xeno stayed seated where he was, facing Senku as his assistant tried to busy himself in his work. He began to sit back, his legs crossing as he spoke, "what you are claiming would go far beyond what we currently know about modern science. Your common campus health center would have no idea what to do with such a case, or worse, they would think you were joking with them." 

Genitals gone... it could mean a few different things. Was Senku entirely smooth now? Something akin to a Ken doll? Or, perhaps, did he still keep a few parts, shrinking down too small to make out. Or, the other option, the one that piqued Xeno's curiosity the most. If only he could convince Senku to allow him to examine his... _ 'situation'.  _

"We both know that you'd best be suited to talking to a man of science. And lucky for you," his arms slightly moved outward, as if showing himself off, "you have me. I may not be as skilled in medical science as others in this facility, but I know my fair share. Enough to help you, perhaps. In fact," Xeno's gaze slowly turned to the door that Senku had closed earlier, one that was usually always kept open during the days, "I have a feeling that was your original intention." 

Xeno slowly leaned forward then, his elbows resting on his knees. "Now then, stand up. If anyone can find a cause and a solution, it would be the two of us, would it not?"

Senku listened attentively to Dr. Xeno’s words, internally cursing himself. Of course the health center wasn’t well equipped, but he didn’t want to waste Xeno or anyone else’s precious time. He took a deep breath before glancing up at the doctor, surprised to see his calm demeanor. 

“Th-thank you… don’t feel any pressure though, I don’t want to distract you from your work.” Senku glanced over at the door, he originally closed it because he didn’t want anyone else to hear, but… maybe he subconsciously was hoping Xeno would offer. 

He stood up, averting his gaze from the man in front of him. It was already awkward enough to say it, but to expose himself was on another level. Did he strip down now? Would Dr. Xeno want to examine him with his clothes on first? Was he just being humored, and his mentor thought he must have taken some hallucinogens? Is he going to get fired and sent home?

He caught himself overthinking and clenched his fists to ground himself, waiting for any instructions. If there was anyone Senku could trust, it was Dr. Xeno, right?

Xeno noted how Senku stood still. Of course he was overthinking this, Xeno couldn't entirely blame him, either. His boss practically just asked him to disrobe himself. Anyone would be concerned of the implications or the repercussions of agreeing to such an action. Senku was so rarely nervous... Xeno became slightly surprised at how delicious he found the concerned look on Senku's face, trying so hard not to look Xeno in the eyes... 

"You're not distracting me," Xeno said then, knowing full well that Senku needed a bit of a push forward, reaching his own hands forward as he undid the young man's belt. "As you saw, today is nothing but a grueling day of paperwork. If anything, you've added a bit of excitement to the day." Xeno's hands weren't being stopped, so he took things a step further, now undoing the button and zipper of Senku's pants. Afterwards, Xeno looked up to Senku, dark eyes locking with his fiery red ones, not looking away as he hooked his thumbs into the hem of Senku's pants and boxers, slowly pulling them down. 

Xeno knew that, in Senku's mind, there was a chance that Xeno didn't believe Senku's claim to be missing his 'private parts'. It began to excite him, in a way, to think of what Senku could be imagining. His mentor so easily falling into the plea to pull his pants down. It would have been a pretty impossible thing to claim, anyway, if Xeno had not known about the substance he put into Senku's coffee. Xeno wondered to himself if he would have gone with such an outrageous claim in the first place, just to be able to possibly become closer to his assistant…

Senku cowered under Xeno’s intense gaze, wondering what exact emotion was lingering in his eyes. He seemed so calm, as if pulling down his assistant’s pants was an everyday occurrence, not any cause for embarrassment or hesitation. At least he believed Senku’s claim, surely if he didn’t, Senku would already be on his way out.

And then Xeno looked down - the shock on his face was something he couldn't control. "Ah," he let out, hands falling from Senku's pants as he began to place a hand beneath his chin, eyes locked on to what he was seeing. Senku was right in his assertion - his cock was definitely gone. Even his balls, entirely vanished. Instead what had formed to replace it was something entirely different. It was even well groomed, just a bit of hair situated above it, perhaps suggesting that Senku already kept himself rather smooth in such an area. 

"I was not expecting this," Xeno said then, his voice calm and not showing his own excitement that was growing. He kept such things at bay. His dark gaze caught Senku's again, arms crossing as he continued, "I don't believe I've ever heard of someone completely swapping out their own genitals for those of the opposite sex. Did you really examine yourself, Senku? Surely you should have noticed."

Senku’s mouth went dry when Xeno finally examined between his legs, he hadn’t actually checked himself, so this was entirely new… He could barely bring himself to meet Xeno’s eyes, and he had to will his jaw not to drop when he said what was actually down there. Swapped out for the opposite sex…

“I-I… um… I was too panicked to actually check myself but… it definitely wasn’t like that when I got dressed this morning.” He wished to pull his pants back up, feeling entirely exposed to his mentor, but he hadn’t been told to cover himself yet. Even so, he held the waist of his underwear, ready to pull it back up so the embarrassment could be partially waived.

A hum came from Xeno. What a fascinating turn of events. So this is what the journal spoke of. Xeno couldn't help but wonder if the previous scientist had a similar result. Would more of the serum produce a full body effect...? There was so much to find out, so much testing already to do...

But Senku's knuckles were white, holding so tightly at his pants, obviously wanting to stop already. That simply would not do! He needed to know the extent, how much of a change has happened! "It's a good thing you have me, then," Xeno said, standing, taking Senku's arms as if to forbid him from pulling his pants further up. "Obviously something has caused this. We shall look into it, find the cause, perhaps if there is a way to reverse it. You seemed to feel ill before you noticed the change, we should take your temperature, perhaps a blood sample. Ah, but, that can wait."

Xeno's hands raised up, taking Senku's shoulders, his grip a bit tight, "there is no reason to look so scared. You are in good hands, Senku. Now," his eyes fell to a spot on his desk, clear of papers and notebooks. "How about you take a seat there, and we can find out just how much of your body has undergone such a drastic transformation."

There was something about the doctor’s grip on his arms that had Senkus stomach fluttering. Had he ever been this close before? Why did it matter, this was a professional, medical situation, right? The mention of a reversal was comforting, but they’d need to find out what had happened first. There was obviously a scientific explanation for it.

Senku followed Xeno’s gaze to the spot on his desk, then shakily moved his coat to provide a bit of separation as he sat down. He didn’t want to accidentally sully anything. His nervous grip moved from his pants to the edge of the desk, as he decided to let his clothing fall and pool around his ankles. Obviously Xeno didn’t want him to put them back on yet.

He moved his body whichever way Dr. Xeno requested, his mind occupied with completely recounting each moment of the day. He woke up late, just enough time to grab breakfast at the cafe in his dorm. Surely it couldn’t have been there. He hadn’t eaten anything else, nor had there been any suspicious characters on the train with him. He didn’t feel anything strange when he was running from the station to the research center, nor when he came in. He was missing something, he knew it.  _ What was different? _

Senku listened so  _ obediently _ . Xeno wanted to praise him, but such a comment may come out... a bit strange, at least during this point of their little experiment. Now that Senku sat atop Xeno's desk, Xeno turned and walked swiftly to his door. He flicked the lock on it, assuring with a quick twist to the handle that it was for sure locked, before flashing a smile to Senku. "Don't need anyone walking in, it would be quite embarrassing for the both of us."

  
  


Xeno walked himself back to Senku, doing his best to not look eager to continue. He needed to look concerned for his assistant, but not  _ too  _ concerned, or else Senku may want to end the experiment. So instead he settled for his usual stern demeanor, but spoke with a calm voice as he laid the palm of his hands against Senku's knees. "First, we should check to see if any other parts of your body have changed. Here," Xeno reached up for his notebook, the same from before, but he made sure to turn the pages to a new page. He handed Senku both the notebook and a pen, showing a kind smile. "Take notes on our observations. If things feel out of the ordinary, be sure to jot them down." 

Senku was grateful for the locked door, as well as the distraction of taking notes. It would help keep his mind off of how positively dirty he felt under Dr. Xeno’s hands, Even with his calm and professional demeanor. His usually messy English was worsened by the slight tremble in his hand, but he could just rewrite them later. This would probably be important information, if this turned out to be some exceedingly strange medical condition.

Xeno wasted no time in unbuttoning Senku's shirt, undoing the boy's tie as well. He needed to see, he couldn't just feel. He didn't wait for permission or even objection as he undid each button, eventually opening Senku's shirt to reveal his chest. "No obvious changes, at least visually," Xeno said, his hands reaching forward, fingers slowly feeling around Senku's neck, thumbs pressing against both lymph nodes as well as his Adam's apple. "No swelling, your thyroid seems to be fine as well. I'd be curious to see your hormone levels later."

His mentor removing his clothes was far too intimate for the situation, and made Senku’s heart skip a beat. The blush over his face quickly spread to his neck and chest as Xeno touched him, leaving a trail of warmth behind his probing fingers. Senku couldn’t decide if this would’ve happened without this development, but he wrote it down anyway. 

_ Skin = more sensitive? _

From there, Xeno's hands slowly moved down to Senku's chest, fingers slowly running in a circular pattern from the middle of his chest to his armpits, "no swelling here, either, it doesn't seem that you are growing any mammary glands, this could be a good sign." Not showing a hint of shame on his face, Xeno brought his thumbs to rub against both of Senku's nipples, tweaking them softly, eyes flicking up to look into Senku's eyes. "Do these feel more sensitive than usual?"

Senku jotted down abbreviated versions of everything Xeno said, nervously tapping the pen on the paper between observations. He pursed his lips as Xeno seemed to tease his nipples, but he couldn’t possibly. This was solely for observation. “I… I don’t have much of a baseline, but… I think so?” Senku quickly wrote that down too, keeping his eyes trained on the notebook instead of the man feeling him up in the most sterile fashion possible.

_ "Oh?" _ A smile, just for a moment, pulled at Xeno's lips. "No baseline, none at all?" Xeno didn't look away from Senku, his fingers now taking each nipple between his forefinger and his thumb, beginning to twist and tug at them. "You mean to tell me, at your age, you've never played with your nipples? Surely you have. Ah, no matter," Xeno let them go, hands falling to Senku's thighs, palms resting on them, "it seems the only change you have gone through is your genitalia. However, the question now is how complete the change is. If this is only a surface change, or, well. If the change is  _ deeper _ ." 

"I'm going to need you to keep your legs wide," Xeno said, lifting one of Senku's legs to remove the pants from his ankle, leaving the leg bare aside from Senku's socks and shoes. "There we are." As Xeno looked up to Senku he feigned a look of concern, placing the back of his hand against Senku's forehead once more, "you're absolutely sweating. Perhaps we should take your temperature before continuing." Of course, Xeno knew exactly why his assistant was so flushed in the face. His legs were wide open right in front of his superior, a brand new set of unexplored genitalia sitting between them. Xeno just couldn't help but tease.

Senku tried to stammer out an excuse, but quickly closed his lips and instead wrote a note about increased sensitivity. He felt a pit in his stomach at the idea of a “deeper” transformation, but he assumed that other equipment was needed to fully confirm that. Hormone levels, blood tests, an ultrasound maybe… he didn’t mind his remaining clothing being shed, this was already embarrassing enough.

He kept his legs spread wide enough for Xeno to see between them, though he quickly looked away and focused on his notes again, waiting for the next observation he needed to write down. Naturally it was about his bright red, humiliated state. “Oh, no, I just…” Senku gave a nervous laugh, “This is just a lot, and… pretty embarrassing, you know?”

Xeno began to nod, "of course it is. This is quite out of the ordinary, isn't it?" Xeno stepped forward, his legs so perfectly fitting between Senku's own, placing his palms against Senku's now bare thighs. "You are half naked, baring all to me. Your body is obviously becoming aroused," one of Xeno's hands raised slowly, tugging again at one of Senku's nipples, which was now standing swollen and pinked, "your body is showing all the signs. You don't need to feel ashamed in that, it's entirely natural." 

"Even here," Xeno made sure to move slowly, a single finger pad pressing against the folds of Senku's new parts, barely slipping between them but able to feel the wetness that had begun to accumulate. "Your body is reacting to me. But this will aid us." As soon as Xeno had touched Senku, his hands entirely removed themselves from his body, totally turning around as he brought his computer chair closer. Sitting into it made Xeno face level with Senku's hips, able to get much more of a better view. "Shall we continue?"

Senku had tensed under Xeno’s firm touch, taking a shaky breath in an attempt to balance himself. What was the point of this, his words nor his teasing didn’t feel very scientific, but perhaps this was normal? Though, Dr. Xeno had said he didn’t know much about medicine, so maybe he wasn’t sure of the proper procedures either. This was fine. The fluttering in his stomach and the heat accumulating in his core at every touch were all fine, normal even. Under such strange circumstances, anything was normal.

What likely wasn’t normal was the disappointment Senku felt when the touches disappeared, when Dr. Xeno turned around to bring his chair over. He’d never been upset when his physicians had stopped touching him, but their probing had always been much more chaste, and Senku was much younger at that point. Surely this feeling must be from an imbalance of hormones, that’s why he was reacting like this. A quick scribble of emotional changes - hormone imbalance? was all he needed to comfort himself a little.

“Y-yes, let’s.”

Xeno gave a warm smile, "what a good boy you are." Just a small bit of praise. It wasn't much but Xeno enjoyed the way that Senku busied himself with his notes, trying so hard not to focus on what his superior was doing. Of course, Senku was going to have a much harder time focusing soon. Yes, Xeno wanted to examine his assistant, see the extent of this change. But being able to see Senku become completely undone at the touch of his hand... that was another desire that Xeno had been keeping buried ever since Senku began to work for him. And now, now Xeno could finally see what Senku's expression would be as he gave in to pleasure. 

Xeno started by pulling slowly at Senku's legs, placing both of his feet on the desk as well. It caused Senku's legs to widen even more, the view becoming even better. "Stay like that now," Xeno said, wasting no time in bringing both of his hands towards the folds between Senku's legs, thumbs slowly spreading the lips apart to reveal the sensitive pink skin within. 

"Astonishing," Xeno said softly, his thumbs still spreading Senku wide as he moved his hands lower, "even the perineum seems to have shrunk. A complete and total change. This could change the medical field forever..." The last comment was more to himself - this compound, if mass produced, could change the lives of many, especially if a reverse effect could be found. The trouble was getting the FDA to approve of such a mutative drug...

Xeno was so close to Senku's groin, able to see the way his body reacted to his touches, the small twitches or clenches to the muscles there. He was still so wet, obviously his body being turned on from being stared at so intensely.  _ Such a naughty boy _ \- Xeno wanted so bad to tease him. But he needed to keep this professional. For now. "In case you didn't know," Xeno began, keeping Senku's folds wide, moving those fingers slowly upward against the sensitive skin, "the human penis has around eight thousand nerve endings. However, the clitoris has over fifteen thousand. Nearly twice as many." Xeno's gaze shot up as the pad of his thumb pressed against the sensitive nub, rotating it slowly, "can you attest to that? How much more sensitive would you say this area of your body feels?"

Senku closed his eyes and made attempts to control his breathing, both from the anxiety and arousal of it all. Of course he had thought Dr. Xeno was handsome, but this was a professional relationship, he couldn’t allow himself to have thoughts like that. Even when his mentor was examining his new intimate area, this was purely scientific. He couldn’t let such thoughts interfere with the experimental process. The praise his superior had given still swam around his head, but surely he was just making a comment on Senku’s note taking. He could barely focus on Xeno’s words, but he still managed to scribble them down through the shame and arousal.

_ Perineum shrunk / complete change _

_ ♂︎ = 8k nerve endings / ♀︎ = 15k+ _

The fingers in his folds sent shivers up Senku’s spine, and he nodded along to the observations. His breath hitched at the sudden pressure on his clitoris, and he bit at his lower lip to keep from making any embarrassing noises. After a moment, he took a shaky breath before nodding. “Th-that… that sounds accurate.” He quickly scribbled down the affirmation in the notebook.

It would be so easy. To continue stimulating Senku until he was nearly at the edge of an orgasm. But Xeno wanted to 'examine' his assistant, just a little more, before sending Senku over that brink. He gave a few more circular massages to Senku's clit, enjoying how it made his knees slightly quiver, before moving his hands away from the mound. It would be better, in the end. Make Senku desire it more. 

Senku’s notes became a little more shaky as time went on, though he didn’t quite understand the point behind the continued stimulation, unless his mentor was trying to tease him, or was getting off on this… but that couldn’t be. Dr. Xeno was a professional, he just wanted to be thorough in his examination. That’s all.

"We can only do so much here, externally," Xeno spoke as he turned his attention to Senku's entrance, once again using his thumbs to widen him, exposing something that made Xeno's face brighten. "So you're intact - or, well, to say," Xeno let a finger carefully prod forward, running against the thin membrane that covered Senku's entrance, a small hole set perfectly in the middle, "you have a hymen. How elegant..." So the serum took Senku to a virgin state. Was he a virgin too, outside of this? Xeno wanted to ask, wanted to ask if Senku had ever even had an intimate experience with someone else. Has he been kissed? None of these questions would help his research into how the serum worked, but they were things he needed to know. At some point, perhaps, he would get the answers from his assistant. 

Senku bit his tongue when he was spread open, it was so vulnerable, but he knew he was in good hands. Xeno was just pushed by a scientific curiosity, he wasn’t intending for Senku’s toes to curl inside his shoes, nor for him to bite his tongue in an attempt to keep himself silent of whimpers.

_ Intact hymen _

The entrance given by Senku's hymen was small, barely the size of Xeno's pinky, but the membrane was elastic and could be pushed back easily with some gentle maneuvering. Breaking him would be too much, as enticing as such an act would be. Oh, how Xeno imagined it; two fingers ramming past the barrier, causing it to tear and pull back. It may be a thin membrane but  _ oh _ how it would bleed...

Xeno had to clear his throat. His fantasies were getting the best of him. Even his cheeks were feeling warm, now. Sitting lower than Senku at least hid the fact that he was painfully hard within his pants, but his assistant couldn't blame him, staring at such a beautiful specimen... "Right," Xeno began, putting his mind back on track, fingers wet with Senku's fluids, using them as lubrication as he began to rub circles around his entrance. "with enough work, we can determine how deep the canal goes, at least. Any further and we will need ultrasound equipment to see what else you have grown..."

Even the single, small finger was a strange enough feeling. Senku forced himself to relax, trying not to tighten down on the digit in an attempt to ignite more of his new sensitive nerves. The maneuvering of the membrane was uncomfortable at best, but he didn’t complain. It was just part of the process. Part of him wished Xeno wouldn’t treat so carefully, like he were a delicate specimen. Though he was grateful for the reduction in pain, at least.

_ Vaginal canal depth = ? _

_ Further examination w/ ultrasound needed _

Xeno did his best to move slowly, not wanting pain to cause Senku to want to end their experiment, his finger rubbing in small circles around Senku's entrance. His body was aroused, the juices nearly pouring from him, soon allowing Xeno to begin to prod his middle finger at the hole. The elastic membrane seemed almost eager as it allowed Xeno to push past it, warmth overtaking his finger as Xeno slowly moved deeper. The canal was so tight, even against Xeno's single digit. Would he even be able to fit two...? He could feel the way Senku's body instinctively clenched around the intrusive finger, but Xeno didn't stop until he was knuckle deep. "We can affirm that the canal reaches at least four inches, which is rather average if I am recalling correctly. Though, that depth does increase with stimulation." It was not needed for Xeno to slowly pull his finger back, only to press it slowly back into Senku. Such a thing was only for that said stimulation. But still, Xeno did just that, wanting to stretch Senku until more fingers could be added. 

Senku let out a gentle sigh when he felt Xeno’s palm against him. It didn’t hurt, not particularly, but there was an odd satisfaction in the pressure and discomfort. He shakily made another hasty note, knowing that he shouldn’t stop with his responsibility just for his own sensations. 

_ Vaginal canal depth = ? 4 in to _

He left the remainder of the line blank, assuming that Xeno would figure out the maximum depth sooner or later.

Xeno...needed to stand. Hopefully Senku was too distracted to look down and see the bulge that had formed in Xeno's slacks. But stand he did, twisting his hand slowly, finding much more ease now in the slow thrusts of his finger. "The next part of this experiment is... not necessarily academical, in truth it is something I am just curious about." Xeno looked to Senku's eyes, not minding if the boy could not stare right back at him, "the difference between a male and female orgasm. Surely you've at least experienced the former..." Xeno's body moved closer, too close to allow Senku to busy himself with notes, Xeno's hand resting on the desk beside Senku's body as his finger slowly curled. "Simply put, Senku, I wish to bring you to orgasm. And for you to tell me exactly how you feel. We can make notes on the experience later."

Senku was torn from his thoughts by the movement of the doctor’s finger inside him, clearly the ‘stimulation’ Xeno had just spoken of. Senku managed to focus his eyes on the doctor’s face as he stood, and nodded slowly at the request. “I… I’ll do my best t-to compare…” He was sweating at the proximity, trying not to let his strange curiosity show, but likely failing.

Xeno grinned - he couldn't help it, the amusement he gained from watching Senku try so hard to stay in control of his mind already. "Such a good boy you are," he purred out, beginning now to move that finger faster. It was true - he wanted to know, he wanted to know everything about this change that Senku had gone under. Perhaps such things as a womb or ovaries did not develop fully, that would be for the best, wouldn't it. No need for condoms, Senku would be able to put this new body part of his to good use. What would more serum do? Xeno wanted to play around with it, tweak it somehow, perhaps add new mutations, new results. The possibilities were absolutely endless, and Senku made such a delicious test subject... 

_ Fuck.  _ There was no way that was just innocent praise, but Senku certainly didn’t mind it. He hated to admit it, but it went straight to his groin and sent his stomach fluttering. He carefully set the notebook and pen down, he wouldn’t be needing them for now. Of course he knew what his normal pleasure felt like, but this was far different. It was deep within him, sending electricity through brand new nerves that made his thighs want to press together, but he was blocked by Dr. Xeno’s presence. 

Another finger - Xeno had to move so gently, Senku's hymen barely allowing the extra intrusion. He had added his ring finger, both of them long and able to reach deep, curling occasionally and rubbing against Senku's walls. More stimulation, though, would be best. Xeno brought his free hand back, thumb laying against Senku's clit, beginning to rub against it in a circular motion. Going nice and slow would have been nice, making Senku slowly edge closer to orgasm until he was begging... but they simply didn't have the time. They couldn't risk someone coming to knock on the office door. So Xeno sped up his movements, thumb quickly flicking and rubbing against Senku's clit as his other hand began to thrust at a faster speed, the wetness around them beginning to make quite the lewd sound with each deep thrust.

Senku did his best to keep quiet, the walls surrounding them were certainly not soundproof, and to be found in such a compromising position wouldn’t be good for either of their reputation. But even so, he couldn’t help the soft cry when Xeno’s thumb started circling his clit. He immediately covered his mouth to keep himself from making more noises while taking mental notes. He’d never been this vocal while alone, but he couldn’t determine if that had anything to do with the change, or simply by being pleasured by another person, he’d have to test that on his own…

Another smirk began to pull at Xeno's lips.  _ How cute _ . Of course it was best that Senku did not call out. A single moan from his office would be hard to explain. Xeno wondered if he could ever convince Senku to lay in his bed... Xeno's city apartment was nice, yes, but would Senku fear the neighbors? He wouldn't have to. They would be envious of Xeno, having such a cute play thing moaning all throughout the night.

"Trying to stay quiet...?" Xeno teased softly, his face moving closer, speaking low into Senku's ear. "Are you often the type to be loud? Or does this just feel good to you?" Xeno never stopped his quick motions, feeling Senku's juices beginning to run down his knuckles and hands, dripping all over the table. "I can't help but wonder, Senku... You agreed to do this so easily. You dropped your clothing for me without even the slightest objection. You've let me sink my fingers deep inside you, and here you are, trying so hard not to call out." Xeno licked softly at his own lips, Senku's neck looking so tempting... He wanted so bad to run his teeth along the perfectly pale skin. "Did you give in easily because you've fantasized about this before? Laying across my desk for me? I'll know, if you lie. I can practically feel your heartbeat through your skin."

Senku bit his lip, not entirely sure how to answer. “I… I d-don’t…” He let out a whimper when Xeno’s fingers brushed against a spot that had his legs quivering. He went silent at the accusations, whispered in his ear to tease him. Of course he hadn’t actively thought about it, he didn’t want to ruin his reputation nor his relationship with his superior. But there were some things he couldn’t help but notice… his face would always heat up whenever Xeno would peer over his shoulder while he worked, leaving very little distance. There were noises the doctor would make when he stretched that would worm their way into Senku’s head when he was enjoying himself alone at night, but he would always try to drive them away by turning up whatever music or video was streaming through his headphones. He slowly nodded, keeping his hand over his mouth. “I… I j-just trust you… but m-maybe I…”

Another grin curled onto Xeno's lips. The boy could deny it all he wanted, but the way his body reacted spoke all for itself. He could prove a point, grind his hips forward, show Senku that this whole ordeal was turning him on as well... but no. No, such things were best saved for later. After Senku knew about the serum, about what was going on with his body. If things went according to Xeno's quickly thought up plan, then Senku would hopefully be willing to let things continue. To let Xeno do whatever he pleased... 

"I'm glad, then, Senku. It's good that you have trust in me." Xeno said softly, letting his breath hit the cuff of Senku's ear. He hoped the trust would last throughout learning of the experiments. Senku's angry face sounded just as delicious as his moaning one... The moaning  _ was  _ nice, of course. Did Senku notice? The soft whimpers coming from his throat, just audible enough for Xeno to hear them. "You're close, Senku... can you tell? Your hips are even moving against me, it's quite cute, actually." Xeno wanted to pull back and see Senku's reaction to being called cute, but he stayed close, words falling huskily into Senku's ear, "I need you to cum for me. Let me feel it."

Senku was panting softly by then, his lips hanging open and his eyes fluttering shut. A sheen of sweat clung to his forehead, and he noticed the subtle movements of his body. The canting of his hips, his hands gripping against the desk until his knuckles turned white. Tiny noises escaped his mouth, barely-there whines and whimpers that would thankfully never be heard by anyone who would happen to be outside. His slender thighs all but clamped down on Xeno’s hand, trying to keep him in.

Cute… he hadn’t been called cute in a while, but for some reason he didn’t seem to mind it when the word hung on Xeno’s low voice. Some last shred of pride wanted to deny it. He wasn’t cute, he couldn’t be cute, he was a grown man after all. But there was no point in holding onto pride right now, not when he was about to come undone on his mentor’s fingers.

At Xeno’s command, Senku tensed up and his eyes flew back open, one hand clapping over his mouth to contain the cry that he wanted to let out. He counted the seconds that his muscles convulsed, the frequency of it. The sensation wasn’t much different than before his unexpected transformation, but it was certainly longer than he was expecting. Finally, all his muscles relaxed at once, and he flopped back against the desk, and his chest rose and fell as he tried to regain his breath.

" _ Exquisite... _ " Xeno said, nearly breathless himself from watching such a show. His fingers were drenched, pulling so easily from Senku's body, remembering so vividly the way his walls clasped down and nearly pulled him further in. Senku's entire frame panted with an exhaustion, chest rising and falling with heavy breaths, shaky like the rest of his body. Xeno looked down to his fingers, examining once again at Senku's folds, slick with mess now. A tiny bit of blood - not much. Perhaps he got too rough near the end, but Senku never made any sounds of pain. It was no matter - such a membrane healed quickly. He'd feel a sting for a day or so. 

"You may want to clean yourself up," Xeno said then, taking his seat once more, legs crossing and hiding his own erection. He didn't feel ashamed of it - but acting unaffected by Senku's little performance brought a bit more fun to the situation. If Senku left to the bathroom then Xeno could very quickly take care of his own arousal. If not, he could let his body calm down slowly on it's own, as uncomfortable as it may become. "It would be good to go over your notes as well. All of them, now that you are in more control of your thoughts."

It took Senku a moment to come down from his ecstasy, but he got up as soon as he could. His legs were shaking like a newborn fawn, but he managed to grab a tissue from his desk to clean himself up before quickly redressing himself. It was almost humiliating, being in such a euphoric state only to be thrust into a professional setting once more, but he supposed that was the nature of studying such things. He quickly grabbed the notebook and went over his scrawl, cleaning up the illegible and writing down the remainder. 

_ ♂︎ orgasm ~10-15 seconds / ♀︎ ~20 seconds, more testing needed to obtain proper time frame? _

_ Sensation approx. the same, took longer to achieve but lasted longer _

“Sh-shall I get back to my scheduled work, sir?” Senku slid the notebook back over to Xeno, and seemed to shrink back into his chair. “Or is there anything else I need to do?”

A smile played on Xeno's lips, though it was a bit forced - perhaps he himself should leave, take care of the throbbing in his pants quickly. To masturbate in the workspace bathroom... very inelegant. But it would help clear his thoughts away from Senku, the way he so nervously was trying to act like nothing happened. It would be so easy to continue these 'experiments', but Xeno didn't have the right tools around to convince Senku into doing so. He could acquire some. He'd have to put in an order online. Express shipping. 

Xeno quickly cleared his throat, standing and straightening out his coat, the length thankfully covering any signs of an erection. "You may resume," he started, walking over to Senku and placing his hands on the backs of his shoulders, "there is something I must attend to." Xeno made sure not to give details - let Senku's mind wander of exactly what Xeno was leaving to do. Would it cause more arousal? He couldn't see how dilated Senku's eyes were while standing behind him, but his skin still seemed flushed and sweaty from before. "I will not be long." 

With that, Xeno promptly left the room, unlocking the door and closing it again behind him. He started his way towards the bathroom, not exactly proud of taking care of himself in such a place, but it would do. 

Senku nodded at Xeno’s order, but his mind tended to wander as he continued to work. What was Xeno doing? Was it related to the “experiment” they had just done? Surely not, it was purely professional, scientific, experimental… he was probably just off to grab some paper, maybe a towel or something to that effect. It was alright…

It didn’t take long for Senku to think of more things he needed to write down, though. The external versus internal sensation being the most important. He cautiously grabbed the notebook and flipped to what he thought was the right page… but it just had a few notes, in Xeno’s handwriting.

_ Put 25mL of serum A in Senku’s coffee, 7:57am. Monitor results when he arrives. Previous tester left no notes of specific change. _

_ No detectable taste, smell, or textural difference. Drank all of it, no issue. _

_ 9:32am, Senku had to leave room. Likely related to serum, monitor closely when he gets back. _

Senku didn’t know how to react. A pit formed in his stomach, betrayal and discomfort boiled in his veins as he quickly put the notebook back where he found it. Should he even let Xeno know that he found out? 

Why would he do this…?

* * *


	2. Experiment 02

**Notes for the Chapter:**

> [Feel free to join the Kingdom of Shipping discord server!](https://discord.gg/zedJR9n)

* * *

Xeno sat next to his coworkers table, nodding as they went through their work, confirming or correcting certain parts of their work. They were thankful for his help. And Xeno was, he supposed, thankful that the focus had caused his erection to leave entirely. It was a decent outcome. At least he no longer needed to try and stay quiet over a toilet. But as the work continued on, Xeno wanted nothing more than to be done with this. His coworker must have noticed, apologizing multiple times until the work was finally finished, followed by thanking him endlessly. Xeno was great at putting on a forced smile, telling them that there was no need for such niceties. He was around to help, after all. But, as soon as he was able to leave, Xeno took the chance, directing his attention back to his office. 

As he entered, his eyes locked with Senku's, able to read the animosity that was being sent through the betrayed glare. "Ah," right. The notebook. Xeno knew there was a great chance Senku would read through his own notes. It was partially the reason he left it there. Senku needed to find out eventually, after all. It was best to put it out in the open early on, and somehow get his assistant to agree to further experimentation. A willing participant would make things easier. 

Though, an intrusive thought in the back of Xeno's mind told him the truth of the matter;  _ even if Senku was not willing, even if it needed to be forced, the experiment would continue. _

Xeno walked to his own desk, slowly sitting in his chair, legs crossing before him, "I suppose you have some questions for me, given your stare. I only ask that you keep your voice down."

Senku didn’t care that his upset was so obvious. Of course he was furious, no one would want to be the subject of an experiment like this. He had admired Xeno for such a long time, and now that he had finally gotten to work with his idol… 

“ _ Why? _ ” Senku tried to keep his voice down, but it caused his words to come out shaky and hurt. “What did you– you didn’t even  _ know  _ what would happen? Is there a way to reverse it?” He held his pen in a white-knuckled grip to keep himself from lashing out. 

What was Xeno even expecting? How long had he been planning this? What was this really for?

Should he leave? Call Xeno’s supervisor, the school’s dean? Tell his dad, ask to come home, see if anyone in Japan was able to reverse this? Surely it would be too expensive to get it checked out in the states…

"Why...?" Xeno blinked slowly at Senku's words, gaze looking upwards as he thought it through. Such answers were obvious to Xeno, but saying all of them out loud would most likely scare Senku off even quicker. The other questions, though, those were easier. "To answer you, no. I had no idea what would happen, hence the observation." Xeno leaned forward as he grabbed the tattered old notebook from his desk, placing it onto Senku's. Afterwards, he opened a small drawer on his desk, placing the two brown bottles up top. "As for reversing, I do not have an answer, currently. It seems the previous scientist had abandoned this project. It is possible he stopped it because the effects wore off. You're welcome to look through his notes as well, it's honestly a fascinating compound."

"As for  _ why _ ..." Xeno sat back in his hand, fingers pressing together, "simply put, you are the perfect specimen. Young, no underlying health issues, and I know you are just as interested in finding the science behind these changes as I am." Xeno began to smile then, his eyes creasing with it, "be honest, Senku. If I had come to you with this serum and asked you to undergo self testing, you would have agreed. You're my eager assistant - in fact you do much more than just assisting, you are more like my partner most days."

Senku felt his stomach drop, staring forward at Xeno as he spoke. He quickly grabbed the notebook, looking over the yellowed pages. Any words that he wanted to say died on his tongue. 

“I… I just…” He gulped, staring down at the old, scribbled handwriting. Xeno’s suggestion bounced around his head, but he didn’t know the answer. “I don’t… I don’t know.” It was clear the compliments and praise were just trying to win him over, trying to earn his trust. “I trust you, but… what is even going to happen now? Do we just wait, or…?”

_ Good  _ \- Senku seemed more calm now, at least in the sense of accepting his fate. "What will happen now," Xeno thought, his foot softly bouncing, "is a mix of research in the serum itself as well as your body. I am sure I can trust you to keep an eye on any new hormonal changes through the night, breast growth, fat around your hips, or even a change in the voice." Xeno had doubts that more changes would happen overnight, seeing as the initial change happened so quickly. But it would keep Senku alert, and observing his body. 

"As for me, I will take a bottle home with myself," Xeno said it while tapping one of the bottles. "I have some of my own equipment at home, I would like to study it at a molecular level, run some tests of my own..." Add a few things if he could... Senku's change was amazing, but the thought of strengthening the change... Xeno didn't have much care about Senku's gender, his assistant was cute no matter what, but there were other changes the body could have thrust upon it... 

"I also intend to buy a few things, or put in request to borrow some equipment, like that ultrasound." Maybe some other things. Some ways to really, really examine his assistant, and put him to the ultimate tests.

Senku nodded slowly as he listened, the blush in his face returning out of shame. How could he have been so stupid, he did exactly what Xeno wanted, completely unprompted. And now, when he could refuse, he was going to continue. Of course he was, he didn’t want to give up this opportunity. It would be okay, Xeno had prestige for a reason, right? And if Senku was going to be his partner… he’d have to cooperate, didn’t he?

“R-right, I’ll… I’ll keep track of anything unusual. But… I should really get back to our scheduled work for now.” He quickly turned around to continue typing at his computer, and to hide his embarrassed face.

He was distracted throughout the rest of the day. Thinking about how strange this situation was, what he would need to do when he got home, if he needed to pick up anything different. He didn’t know if he needed to pick up menstrual products yet, though if it didn’t go away within the month he was sure to find out. He had to make sure his roommate didn’t see anything, maybe he’d stuff a sock in his pants to keep any suspicion off of him…

Xeno's smile only grew. He allowed Senku to busy himself, his embarrassment being something Xeno was growing very addicted to seeing. Xeno turned in his seat as well, returning to work, finding himself working through his projects quicker than usual, wanting them done as soon as possible so he could busy himself with much more important matters. He occasionally chatted with his assistant, their usual daily talks, but there was a definite new tension in the room. Xeno loved it. 

Senku forced his mind to focus only on his work, and counting the seconds until it was time to leave. The tension made his skin crawl, but this was his job, to do what Dr. Xeno told him to do. He bounced his leg to hopefully release some of the energy that was building up inside him as the end of the day grew nearer, until finally he finished his last task of the day. 

Xeno noticed how much quicker Senku worked as well, perhaps wanting to get out of the office for the day. He would have to check his work later for any errors. He turned to Senku once his last bit of work was turned in, looking at the notebook on the table which held all of Senku's earlier notes. "Your homework for the night is only to note any other changes, if you notice them. Otherwise, rest. Your body is sure to be exhausted after expending so much energy to such a change." 

Senku nodded at Xeno’s words, unusually silent as he packed up his things. He was thinking more about the ride home and his roommate. Would anyone notice something different? Probably not, but he was still going to be thinking about it. He’d also have to be sure to get to bed early, so he has enough time to make his own coffee in the morning.

Xeno stood then, walking a little too close to his assistant as he picked up the old tattered journal. When Senku looked up, he took an instinctual step back when he noticed how close his superior had gotten. 

"As for me,” Xeno began,”I will scan these pages and email them to you. I welcome you to study the compound as much as you want. These, however," Xeno was sure to pick up the bottles, not knowing if Senku was the type for revenge but wanting to nip that idea in the bud before it could ever form in his assistant's mind, "will be staying with me."

“R-right… I’m sure the compound is quite interesting.” He nodded quickly, holding the strap of his bag tightly. He hadn’t even been thinking of taking the bottles… granted, it would have been a nice payback, but surely he wouldn’t have gotten anything out of it. 

"That is all, then, you may go."

At Xeno’s dismissal, Senku waved goodbye before leaving the office, walking quickly in order to get to the train on time, as well as to leave the center faster.

Xeno watched as Senku quickly fled the room, a grin growing on his face. There was a thought in the back of his mind that Senku may not return the next day. But he knew his assistant better. His mind was too thirsty for knowledge, and Senku was also aware that being an intern at NASA was something he would be foolish to throw away. So Xeno was very, very sure he would see his assistant again the next day. 

Xeno gathered his things, making sure to add the old journal as well as the bottles of the compound into his bag before heading his own way out. A few coworkers waved his way but Xeno only politely nodded. He had no intention of staying after work and chatting with colleagues. He had a lot of work to do at home. 

* * *

Under a microscope the serum was quite active. Xeno had added small droplets of the mixture to a few cultures, eager still to learn more about it. To be able to change Senku's body at such a molecular level.... if Xeno could learn everything he could about this compound and make more... there was no telling who in the world would be after such a chemical. 

Most of the night was spent researching the serum, adding other chemicals or ingredients into the cultures to see what sort of reactions would take place. Xeno had a theory - it wasn't a strong one, but if it worked he would probably be up for a nobel prize if not more. He just needed to do a few more tests, a few more additions... Xeno didn't have a lot of interest in money, he already had enough of that to live happily. But the recognition for his work, as well as being able to be in control of how it was used... that was worth learning more.

Of course, there were other things worth learning. Xeno did do as he said and scanned photos of the journal, emailing the images to his assistant. He had not received any messages, but that was to be expected. Senku was still probably quite humiliated after today. 

There were also a few other things that Xeno needed, sent to his house through expedited shipping. They would be at his door step by tomorrow night. A speculum and gloves were the easiest things to buy. An ultrasound machine was far too much money to buy but he knew of places that would rent out the machine for scientific uses, and this was for  _ sure  _ a scientific use. And there was, of course, a few other things Xeno bought. Things that luckily came in unmarked boxes. Things that he couldn't wait to use on Senku... 

* * *

Senku’s train ride home was thankfully uneventful. He spent some time going over his coursework for the week, then watched a few episodes of a show on his phone to pass the time. He thankfully had his work cut out for him, no time tonight to worry himself too much with bodily changes, but he’d keep his eye out for any obvious developments. 

His roommate didn’t seem to notice anything off, the two only exchanging a nod as Senku made his way to his desk. The other freshman had grown used to Senku’s busy schedule and avoidance of casual conversation, but he didn’t mind. All he needed to know was whether Senku wanted him to make two servings of ramen instead of one. The answer was usually yes.

It didn’t take much time for a bowl of noodles to be placed next to Senku, adorned with half a boiled egg and some green onion. It was a symbiotic relationship: Senku made coffee and shut his lights off by 1, his roommate made instant ramen and didn’t play his music too loud, nor did he ask what Senku was working on if he didn’t want to listen to an hour-long ramble.

Halfway through his homework, Senku noticed the alert that he’d received a new email: the scans from the notebook, as promised. He took a little while to look it over. The main compounds were  _ phthalates _ , and  _ xenoestrogens _ , a very ironic name considering who gave him the compound in the first place.

* * *

The next morning, Senku was careful not to sleep in. He made a pot of coffee, pouring half into his travel mug, and leaving the other half in the pot for his roommate. Normally he didn’t have to work on Saturdays, but a launch was coming up, and that required all hands on deck. The train ride went as normally as any other day, and he noted the time once more as he entered the center. 8 hours, 17 minutes, 54 seconds. Still late, but Xeno never seemed to mind.

Xeno didn't get much sleep, but that wasn't an uncommon thing. He yawned in the NASA employee lounge, slowly obtaining his morning coffee. He did not get one for Senku, the boy would be too weary to take more coffee from Xeno now. Which was a pity - Xeno had completed the changes he wanted to make to the serum. He was eager to see how they would work, and if it would work in the ways he predicted. But this was fine. Xeno would wait for the opportune moment. He would find an opening, somewhere. 

Even if he had to make it himself.

Xeno gave his assistant a warm smile as he walked in, intent to not even talk about yesterday unless it came up. Today was a big day, and Xeno knew that his assistant was eager to know exactly what his work would be today. If Xeno was a cruel person he could give Senku endless tasks to busy him throughout the day. But Senku was lucky that Xeno found his excited faces too cute to just toss away. 

"I believe this is your first launch," Xeno said, walking alongside his assistant, sipping at his work-room coffee. "Well, at least not watching from a spectator view. What you'll see on the inside is a lot different. Which reminds me of today's work," Xeno gave a long sigh. He, technically, had a lot to do today, though a lot of it was in the form of overseeing everyone's work. "You can take some time off, if you wish. You're allowed to wander about, watch everyone, get a real good look at the launch. You can tag along with me, though you may find it rather boring. Ah-" he had only just remembered the last bit, "after the launch there will be a celebration in one of the conference rooms. Interns are allowed to come, though you won't be allowed to drink the alcohol."

Senku nodded intently as he listened, his nerves from the morning fading away at the prospect of getting to see everything about a launch from behind the scenes. His mind wandered with all the places he would want to be, at which time, who he was going to observe, whether they would let him or not… he had a tiny subservient instinct that told him to follow his superior around, but he knew that straying from the path would be much more interesting. He just had to be at the station by 10:45 to catch his train home.

The day went all too fast for Senku’s liking. There simply wasn’t enough time, or too many places to be, in order to see everything he wanted to see. He spent the majority of his time wandering around the center and peeking into open doors, occasionally stopping to watch for longer, or to ask questions about the proceedings. The only breaks he took were to grab a quick bite of lunch, and to retrieve his forgotten coffee cup from Xeno’s office. The remaining coffee had since gone cold, but Senku didn’t want to waste it. 

Watching his father’s launch on TV just a couple years ago was exhilarating enough. But this one, watching a rocket take off halfway across the country, surrounded by those that made it possible, knowing that he made it possible, too… everything left his mind. All his classes, his roommate, the serums, his superior’s hand on his shoulder, none of it was real. Not now.

He was still in a euphoric haze as he was dragged off to the conference room for the celebration, it didn’t matter that his watch read 10:32, all that mattered was the beautiful hunk of metal currently blasting into orbit. Something Senku had contributed to, even if just by a tiny percentile.

_ He really was such a naive boy...  _

Xeno kept his eye on Senku for most of that morning. Everyone was busy with their own tasks that day, too focused on their work to really pay any attention to what was happening in the background. Xeno did not expect Senku to mindlessly leave his coffee unattended. Xeno was even in the same room at the time. But his assistant was excited to monitor everyone's work. He had worked hard to get here, after all. 

Xeno almost felt bad for Senku as he stirred the new and improved serum into Senku's coffee mug. Only almost. The effects of this round should be much more extreme than last time, if Xeno's calculations were on point. He left the room then - better for Senku to come and get the coffee whenever he remembered and for Xeno to not be in the same room. Let the boy trust that nothing was wrong, let him enjoy the launch. 

The day was long, grueling in a way, even if it had an air of excitement. Everyone cheered loudly as they watched the new shuttle be sent off into the air. Xeno was as quiet as usual, sipping his own unaltered coffee, his gaze switching from the screen to his eager little assistant. Senku's face was bright, happy, even his eyes shined a bit as he watched the shuttle launch. But there was no change! Nothing at all. Yes there were times that Senku had escaped Xeno's line of sight, but during the times Xeno had seen him he noticed no sign of fever, upset stomachs, not even a bit of sweat. Xeno watched Senku finish off that coffee. Unless his assistant emptied it and replaced it with new coffee…

Xeno gave a sigh as he was ushered off into the conference room with everyone else. Usually he skipped these things, never one for loud parties. But he felt the need to attend this time. To watch Senku. Notice any changes. And to also make sure his little assistant didn't drink any alcohol. 

He neared Senku, his smile kind, "I'm glad you decided to join the celebration. I wasn't aware the trains ran this late. Would you be needing a drive home?"

Senku glanced up when he heard Xeno’s voice, it was the first time they had properly spoken since that morning. “What do you mean…?” He quickly checked his watch and stopped in his tracks, gritting his teeth and mumbling under his breath. “Shit… if I leave now, and run the whole way, I might be able to get to the station on time… but I have to stop back at the office to get all my things…” He turned on his heel, making quick strides towards Xeno’s office, not caring for the group of people heading the opposite way. Senku really didn’t want to get a ride, knowing that it was over an hour’s drive, and that Xeno probably lived nearby. It looked as though most of the interns had already left, or they may be going to school nearby too…

Xeno had to act  _ quick  _ \- he could not let Senku run off right now! He needed to be under constant supervision until the change could be documented! He followed in pursuit, arm outstretched as he grabbed at Senku's wrist. "Nonsense!" He said quickly, showing what he hoped was a kind smile. "You aided in this launch, you deserve some time to relax. I don't mind driving you home." 

Even home -  _ No _ . Senku couldn't be allowed to go home. Xeno needed to think of something, and fast. The quickest solution would be Senku getting drunk. But there were too many eyes around the room, no reasonable adult would allow the young intern to drink. And Xeno was sure that Senku would turn down any requests to stay the night at Xeno's apartment.

Xeno gently pushed his hand against the small of Senku's back, turning him back towards the party. "If you are worried about the long drive I can always offer you to stay at my place for the night." Yes, he'd probably say no. But Xeno at least felt the need to offer before turning to much more dire means.

“I’m fine, really, I don’t mind going home…” Senku wanted to keep moving back to the office, but each moment he wasted meant a closer call at the station, and by the time Xeno was pushing him back down the hall, he knew that he wouldn’t be able to make it in nearly enough time. “I-if you insist, but… I really hate to be a bother, I’m sure you don’t want to drive that far.” Staying at his superior’s house just wasn’t an option, not after the fiasco yesterday. ”I guess it’s fine, though, if you don’t mind going out of your way…”

By the hand on his back, Senku knew Xeno’s true intentions about all this. He’d be responsible though, he’d stick by the few remaining interns, he wouldn’t drink anything unless offered by someone besides his superior, it would be fine. He’d be just fine.

Xeno gave a small sigh of relief as Senku began to conversate with the crowd. Good. He was staying - and hopefully he stayed for a bit longer. Xeno waited patiently until Senku seemed focused and drawn into a conversation between some of the launch overseers and the other interns. If Xeno was lucky the conversation would last a short time. He didn't need long. He knew what chemicals he needed. 

It was a short trip to the center chemistry laboratory. Most of the chemicals required access to a locked cabinet - which, of course, Xeno had keys to. Xeno made quick work of gathering the right chemicals - the exact amounts here were important. This was not a medicine that Xeno knew off the top of his head, of course, but recent events had caused a small curiosity in how it could be made. This would be easier if the laboratory carried rohypnol, but there were little uses that a space center had for such a drug. 

Xeno made sure to clean up after himself, leaving no evidence and leaving the laboratories with a very small vial of white powder. This was for Senku's own good, in the end. If he were to suffer some sort of change that inhibited him somehow, well, Senku would need someone nearby. Someone who knew exactly how to deal with such a situation. Xeno was only watching out for the boy.

Xeno was relieved to see Senku still lost in conversation. Perhaps a little too lost, eyeing the exact moment when Senku sat a small glass down on a nearby table, needing both of his hands to excitedly explain something to the crowd around him. Still such a naive boy. Xeno barely even needed to put on an act, walking casually to the table and avoiding Senku's direct line of sight, leaning over the table as he grabbed a drink himself - and so casually let the powder sprinkle into his assistants cup. It was not alcoholic, but the powder slowly fizzled as it sank, soon disappearing without discoloring the drink at all. The table was facing no one else - no one had seen. Xeno removed himself from that table, holding a glass of champagne for himself as he walked away to find a proper place to sit and watch if his adorable assistant would fall for the same trick three times. 

And of course it happened. Xeno's smile grew as he sat at the edge of the room, legs crossed and watching as Senku slowly raised that drink to his lips. Perhaps the third time really is the charm. Xeno took a small, single sip from the glass of champagne, as a small treat. He could not be getting drunk tonight. He would be driving home, soon.

Senku quickly forgot about his stresses as he talked with the other interns, excitedly retelling his high school escapades of sending dolls into orbit. Any worries about the train, Dr. Xeno, his drink, were far from his mind as he recounted the extensive trial and error until he was finally able to conduct a successful launch.

It was only half an hour until something felt off. His eyes started to feel heavy, and it was getting harder to keep his balance, surely the excitement of the day was starting to kick in. He was familiar with the adrenaline rush that came with successful endeavors, but this felt like more… maybe it was time to go home.

Thankfully, Xeno was nearby, and Senku tugged on his sleeve before leaning on the chair his superior was sitting in. “Hey, um, I think… I think I’m ready to go home now.” He rubbed his eyes, trying to blink away the heaviness. “I know it’s still early, but I’m really tired…”

"Ah," Xeno did his best to hide his smile as he stood. It hadn't been to long, but this was how the drug worked. Twenty or so minutes to feel the effect, around an hour to lose most control of the body... and in a few hours time Senku would be completely out to the world. Xeno slowly led Senku from the party, waiting until they were out the main doors of the conference room before 

he spoke to his assistant, "don't worry - I usually find these things boring. I don't mind going early," it turned Xeno into a bit of a hypocrite - he did just recently force Senku into staying, but hopefully Senku wouldn't catch on to it.

By the time they reached the car lot Xeno had to wrap his arm around Senku's waist, pulling his arm over his own shoulder as he got a better hold on the wobbling boy. It was surely taking effect now. As he slowly helped Senku into the passenger seat of his car, Xeno was sure to flick the child safety lock on before closing the door. Last thing he needed was Senku to feel any sense of panic and try opening the door. 

Xeno didn't speak too much on the way to his place. Senku seemed to be rather sensitive to the drug, already losing much control over speech. He was such a smart boy. Clever. Did his mind know what was going on? Was he trying to fight off the drug? Did he realize what was happening, and was just not able to react properly? Xeno would ask, later perhaps.

Senku stared blankly out the car window as they drove, eyelids barely managing to stay open as time wore on. He’d never felt like this before, did Xeno do something? When could he have? He wanted to ask what happened, where they were going, but his tongue felt heavy in his mouth.

The drive was short. Way too short to have gone to Senku's dorm, though it wasn't as if Xeno asked for directions to the university campus anyway. 

Senku swayed as Xeno let him out of the car, leaning most of his weight on his mentor. This definitely wasn’t his dorm, but it was certainly too late to do anything about it now. All that mattered was getting to a bed, a couch, a rug, somewhere he could lay down and finally pass out properly. 

Carrying Senku across the apartment parking garage was definitely harder than the NASA center parking lot. At least then Senku's feet seemed to be working. Xeno prayed as he entered the elevators that no one would see him dragging a half-asleep young man to his apartment. 

Luckily, Xeno didn't meet eyes with anyone else as he led Senku to his front door, but that didn't make the trek any easier. By the time Xeno was able to lead Senku into his bedroom and drop the boy onto his bed Xeno had definitely gotten a work out. He took a moment, hands on his hips as he breathed deep. He was not fit enough for something like this. 

Senku laid, half coherent, staring back up at Xeno. "It's fine," he said, beginning to loosen his tie as he cooled his body down. "This is for the best, I need to watch over you for the night. Though," Xeno looked down at Senku's body. All this clothing simply would not do. He needed to watch for any and all changes. 

Xeno began to lean against the bed, putting his weight on his knee as he began to undo the buttons of Senku's shirt. "We'll need you in the nude for this exam."

For Senku, the journey from the car to the apartment was a blur. One moment Senku was trying to drag himself to the elevator, the next he was flopping onto a cushy bed. Immediately he started to curl up, his eyes finally fluttering shut. He barely heard Xeno’s words, but he did notice the cold as his clothes were removed. He let out a low whine, curling in on himself to keep his clothes on.

"Now, now," Xeno's hum was soft, but his shove against Senku's body was far from it. If Senku was sober then this would have been a hard task, but his tugs or pushes against Xeno's frame were greatly weakened by the drug. Xeno only needed to push with his body weight, leaning against Senku's shoulders to help uncurl his body enough to eventually remove his shirt. Xeno wasted no time in continuing, his fingers fast on Senku's belt and zipper, fingers curling into his pants and underwear as he yanked all garments down. It was fine if Senku curled up or tried to kick away now - the hardest part was done. Xeno also removed shoes and socks from his assistant, eventually leaving the boy bare. 

"There we are," Xeno said, total adoration dripping from his tone. He turned to a thermostat on the bedroom wall, clicking it to a higher number. "No blankets, now. I need to be able to watch your body." 

Xeno left the room only for a moment, having to dig in a hallway closet for a very important piece of equipment for this experiment. Once he brought the tripod and camera into the room he saw how Senku had once again curled into himself. Xeno quickly set up the tripod, the camera clicking easily into place, and hurried himself to sit on the edge of the bed, an hand outreached to gently pet at Senku's face. 

Xeno hushed his assistant softly, clearing hair from the boy's sweating forehead. "Do not fret. The drug will only last around twelve or so hours. The dose I gave you was quite small. You will rest, and you will wake tomorrow feeling refreshed. But," Xeno's hands pushed hard on Senku's legs, forcing his body to uncurl once again. "I need you to be compliant, for the night."

Senku didn't seem to entirely register Xeno's words, but his furrowed brows pulled at something in Xeno's stomach. Why did they excite him so much? Xeno had to lean forward, pressing a kiss between Senku's knitted eyebrows. "My dear boy," he purred. Being surrounded by the walls of his apartment was beginning to wipe away at the more collected demeanor he held at work. "You will become a beautiful specimen. In fact, I would go as far as to say you already are." 

The hand that held Senku's hips in place soon slowly rubbed at his thighs, even daring to dip between them, fingers slowly brushing against Senku's slit. "Allow me to help lull you into sleep," Xeno whispered, a kiss being pressed below Senku's ear as his fingers delved between the folds, eager once again to feel his assistant become wet for him.

Nothing seemed quite real as Senku teetered on the edge of consciousness. He barely had the energy to keep his eyes open, let alone to move or resist the way Xeno was moving his body around. Objects only seemed to exist in the peripheral of his mind, whether it be the camera or the clothes that were tossed to the floor.

Xeno’s words sounded like a lullaby even if the words would have been concerning to Senku’s fully conscious mind. Drugs, compliance, specimens… he could barely put it together, just enough information to worry, but not enough to break him from his stupor. It was likely that nothing could.

Not even the fingers that pressed into his still new, still painful sex. Only a low whine managed to escape his throat as his thighs made minuscule movements to close. There wasn’t much he could do though, not when he was like this. He could deal with it in the morning, everything would be better by then.

"Shh, shhh shh," Xeno kept up with the small hushes, whispered right into Senku's ear. He made sure to continue to slowly pet back Senku's hair in a calming motion, caressing his cheek and letting his lips slowly trace along Senku's jawline. He could kiss him - but  _ oh _ , what a  _ waste  _ it would be. Senku wouldn't be able to kiss back - or better - to fight against it and whine. Even now, Senku was giving such delicious little whimpers as his hips tried to wiggle from Xeno's grasp. But it was no real use - Xeno's hand was rooted within Senku's folds, and he was not planning on stopping now. 

Was this part for science? No. Not one bit, not really. Xeno knew better than to lie to himself. This was simply... fun. It became so obvious to him the other day as he watched Senku shiver and moan on his desk, his legs so wide and welcoming to him. Xeno wanted more of that. Being able to gain scientific knowledge from the ordeal was simply a bonus. Xeno wondered in the back of his mind how easy it would be to break the boy... how much would it take to cause Senku to become entirely his. A cute little pet to keep, to never share. Senku was the ornery type... it could take a while. But this new drug would help…

Senku fought hard to keep his head amid the tumultuous mix of suffocating lethargy and the pleasure between his legs. He let out noises of protest as much as he could, pushing back against Xeno’s chest, trying to close his thighs, but these objections seemed to only encourage the doctor. 

Much to his disdain, the assault was unfortunately pleasurable, but there was obviously no curiosity behind it, there was probably little scientific endeavor in the previous day’s ordeal, but at least he was able to pretend with his fervent note taking. Now all he could do was lay back and take it, staring up at his superior with blurry, half-lidded eyes.

Xeno never stopped with his hand, teasing Senku's clit until he could feel how much more wet the boy had become. His fingers continuously rubbed in soft circles until Senku's body finally started to calm, losing itself both to the drug and to the pleasure taking over. Xeno soon pressed his two middle digits into that warm wetness, letting out a soft moan himself as he watched Senku's hips arch with the sensation of the invading fingers. His pace started fast and deep - this wasn't a time for foreplay - no, Xeno would have all sorts of fun with Senku later. For now, Xeno wanted to see how fast Senku's body would give in. His palm continued to grind against Senku's slowly swelling clit as he continued the rhythm, pulling back to watch his assistant's body absolutely writhe beneath him. It didn't take long at all before Xeno felt Senku's walls begin to clench around his fingers with it's release.

In any other situation, it may have been romantic. The careful attention paid to his sex, the kisses along his jaw, all sickeningly affection. Senku might have been willing to do this with his superior if he had been asked… hell, he would be more than willing, he’d be chomping at the bit to please Xeno in any way he could, but that chance had long since passed, and the thought was ejected from his mind as he came. 

By the time he relaxed again, it was near impossible to open his eyes, let alone move any other part of his body. Xeno probably wanted that anyway, it would make his observations much easier.

"There we are," he looked so perfect. Xeno was able to move Senku's limbs where he needed them, barely any push back now. He didn't aim for any provocative poses - only having Senku lay flat out, arms at his sides. Once in a good position Xeno got up from the bed, bringing the tripod and camera closer, adjusting the view until he had Senku in a perfect shot. Long cords were placed into the camera - not recording to a single tape or disc but instead straight to Xeno's computer, where he could monitor throughout the night. 

Xeno still saw no changes in Senku's body. This was all right. It could mean that Senku did not end up drinking the coffee that had the serum in it, but that was no longer an issue. Xeno had more, and he now had Senku in his apartment. He only hoped they would not have to resort to the restraints he had bought. He would hate to have to bruise Senku's slender wrists, but drastic means have drastic measures after all. 

Xeno left his assistant in his room, taking a moment to pick up Senku's discarded clothing and place them into a small laundry room before walking out into the main living room of his apartment. The whole thing had a very open floor plan, making it look larger than it really was. But Xeno liked to keep his work and leisure mostly separate, so he made his way to a small office. Long cords led the way, hooked to a modem within the office - it was not a very elegant set up at all, but Xeno didn't have much time to set up. It would do, for now. He could debate setting up proper cameras later.

Xeno always found he had a little too much work to be done. Perhaps he took on too much. He busied himself with his usual night-time duties, occasionally looking over to his second screen which he had set up to only show Senku. Still no changes to be seen. Occasionally Senku would move an arm or a leg, but for the most part his body seemed entirely unconscious. But at some point during the night Senku had managed to turn his body. Not entirely - but enough that it made a harder time for the camera to pick up changes. 

Upon entering the room Xeno made sure to switch the camera off. No need to record a simple rearranging. He slowly pressed and tugged on Senku's body, easily bringing him back into view. It was almost too easy, Xeno taking a moment to check his assistants pulse. Around 55 bpm. Not dangerously low, for a sleeping heart rate, especially for a young man. No sign of a fever, no sweating. Xeno worried if the sleeping drug and the mysterious serum could negate one another or, even worse, mix dangerously. But, to a stranger's view, Senku was just sleeping peacefully. His arms could be moved with no effort. Posed like a doll. 

Xeno let out a contented sigh. Perhaps this was one of the best times he would have? He allowed his hands to slowly roam his assistant's body. So slender, but not malnourished looking at all. Cute pink nipples, ones that hardened with the slightest of teases. Xeno took his time, letting his fingers memorize all of Senku's body. How would the serum change him next? What new places would Xeno be able to explore?

There was absolutely no resistance as Xeno widened Senku's legs. He had taken quite a bit of time the other day examining his assistants new sex, but it still felt so new and unused. Perhaps Xeno would have to change that - how would Senku look when he was totally used up? Would the pink skin become bruised and swollen. Would he retain the tightness that Xeno could feel against his fingers just earlier that night? Xeno needed to feel that again, just for a moment, sliding his fingers across the still moistened skin, easily able to delve his fingers past Senku's entrance. 

His body barely registered it - a bit of a pity. Not as fun as before. With more teasing slow thrusts Xeno was hopeful that Senku's body would react. And it did, just not in the ways that Xeno wanted. Xeno could feel as Senku grew wetter, but it was just about the only reaction the comatose body was giving him. Senku was basically, in that moment, a warm and breathing sex doll. Which Xeno wasn't too keen on. It was Senku's pathetic and whining reactions that made it all so desirable in the first place! He wanted to see his assistant glare at him with flushed cheeks and deep brows, totally denying the fact that he is enjoying the treatment just as much as Xeno enjoys giving it. 

With a sigh Xeno ceased his actions, pulling Senku's legs back together. He turned the camera back on, adjusting the view just slightly before returning to his office. Senku stayed in that position for the rest of the night, Xeno occasionally glancing over, hoping to see some sort of change. 

Eventually Xeno found himself with his arms braced against his desk, using them as a cushion for his chin. His eyes watched Senku slowly, his own lids becoming heavy. Just a small nap - he's taken many naps at his desk before. A small nap and by time he wakes up, perhaps, he'll finally see a change.

* * *

Senku had never slept this late in his life. The clock ticked by 9, 10, 11am before his eyes finally opened. His head felt like it was splitting open, and every bone and muscle in his body ached. He sat up and rubbed his eyes, blinking slowly as his eyes adjusted to… decidedly not his dorm. It was clean and spacious, with a king size bed and a camera, which Senku quickly crawled over and turned off.

The next issue to deal with was his lack of clothes, and considering the disappearance of the clothes he was wearing the night prior, he went to dig through the dresser to find at least underwear and a t-shirt. God, why was all the furniture and clothes so big? He must have gone home with one of the other interns or something, a couple of them were much taller and more muscular than himself…

Once he was dressed in an overly big t-shirt and a loose pair of boxer briefs, he finally caught a glimpse of himself.  _ Was  _ it himself? It had to be, but it was…  _ different _ . His eyes were bigger, his cheeks were rounder, he was somehow even skinnier than normal, and he was  _ much  _ shorter.

_ What the hell had happened last night? _

* * *


	3. Experiment 03

Napping upright in a chair never really gave way to a restful sleep. It wasn't long before Xeno was wincing himself awake, stiff body pressing against his desk as he tried to force himself to stretch. He knew how bad it was for him, but did not want to leave the screen during the middle of the night. Which seemed to be a very understandable worry, seeing as when Xeno finally did look to the screen that should be showing his assistant, he only saw darkness. 

Did Senku awaken...? Did he perhaps run from here - take the camera? Xeno stood, feeling a bit of panic wash over him as he made his way back towards his bedroom. So many horrible scenarios could have overcome his assistant. The camera probably looked so shady to someone just waking up! No sexual acts were caught on that camera, Xeno could attest to that, but he would not blame his assistant for thinking otherwise!

When he saw Senku's frame still in his bedroom Xeno let out a relieved sigh, "so you're awake." But, upon further focus, the person he was looking at... was  _ not  _ his assistant, at least not the same body he had laid into bed last night. 

Or,  _ no _ . It was the exact same body. But it was shorter -  _ younger  _ \- body regressed like some sort of reversed aging miracle. "Amazing," Xeno's eyes shined as he walked further into the room, having to lean down to be on the same eye level as his assistant. "How do you feel? Do you know who I am? Did your memories regress with your age, or has it just been your body?"

Senku’s stomach dropped the moment he heard Xeno’s voice. Of course,  _ of course _ he was behind this. He must have slipped up yesterday, but it was too late to berate himself now. As if one secret body modification wasn’t already bad enough, he looked like a child now. He couldn’t possibly go back to school or work like this, but Xeno had said there wasn’t a reversal yet. What was going to happen now? He listened silently to Xeno’s questions, his face contorting into a scowl as he kicked his superior in the shin. “Of course I remember, now what the hell did you do?!”

Xeno moved back with a small gasp, but quickly covered it with a chuckle. So Senku was feeling himself! That was great! The sleeping drug seemed to have no adverse effects and, well, the serum itself seemed to have worked! Such an impressive change! Maybe this was why it took over twelve hours to take effect? 

Xeno gave a wide smile to Senku's accusations and demands, his hands moving up as if to show his innocence, "I did nothing," he began, though stopped, looking upwards as he thought back.  _ Okay _ , he did quite a lot. There was no use hiding the truth from him now. "Well, I did give you an edited version of the serum. I had no idea what the effects would be, though I had a few guesses. There was a chance it would have reversed the previous effects, but there was also a chance for, well," he gestured to Senku's entire body, "this. Hmm, I'll have to pick you up some new clothes. What size would you say you are, now?"

Xeno didn't wait for Senku to answer before continuing, "as for why you are here, it is simple, I needed to watch you for any changes. That was what the camera was for as well," he looked to it, feeling a new sort of excitement fill him, "your change was most likely caught on camera - that will be amazing to watch."

Senku stared at Xeno in disbelief, his mouth hanging slightly open as he listened to the rambling. “ _ Clothes _ aren’t exactly what I’m worried about right now, I’d much rather you spent your time on trying to figure out how to fix this.” He crossed his arms, his frustrated face reading more as a pout with his rounded cheeks. 

“I doubt the transformation is going to be very pretty anyway, I’m just glad I was asleep for it, considering how much it hurts.” Indeed, Senku’s skin was now covered in bruises, he could only imagine that his bones had fractured and fused back together somehow. It wasn’t the most scientific explanation, but people don’t just shrink.

"Those will fade," Xeno said, slowly kneeling again. It was true - Senku was covered in small bruises. In a way it seemed that drugging Senku really was for the best. He had slept through the worst of the transformation. Rohypnol was sometimes used clinically as an anesthetic after all, so it made sense. Senku should be thanking Xeno - but he kept such things to himself. Senku did not seem like he was in the mood for being thankful. 

"Come, then, it is the weekend so do not worry yourself over school and work for now." Xeno walked from his room, leading Senku towards the open kitchen. He gestured to the small dining table, trying to coax Senku into sitting, before grabbing a glass from the cabinet. He filled it with water from the sink, placing it in front of Senku with a slight smirk, "water - straight from the tap. Not doctored in any way," he followed that by opening another cabinet, pulling from it a small white bottle. He placed it in front of Senku as well, taking a seat across from him. "Ibuprofen - it's legitimate, you can check the markings on the pills themselves." Yes... Senku probably wouldn't trust him with eating or drinking for a while. A small price to pay.

Senku watched Xeno carefully, his eyes not leaving the doctor’s hands as he brought over the glass of water and bottle of painkillers. He narrowed his eyes as he scrutinized the pills, they did indeed look identical to the picture and description on the package, and the glass had looked clean before Xeno had filled it. Even so, he held out a pill and the glass to his superior, eyes narrowed. “You first.”

Once Xeno had taken the pill, Senku took three painkillers and finished off the glass of water before sitting back in his chair. He crossed his arms and swung his legs, still regarding everything around him with suspicion. He was sure no one could blame him, far too many of his drinks had been doctored for him to have any trust in his surroundings.

“What now? You figured out what your serum did. I can’t stay like this forever…” He leaned his head back, staring up at the ceiling, before glancing back at Xeno. “If you bring me my phone, I can ask Taiju to send me some old pictures, so we can figure out how far back I went.”

Xeno hummed happily in agreement, nodding as he stood and walked to the laundry room. It did not take too much digging to find Senku's phone in the pant pocket. He debated, for a moment, how much of a good idea this was... Would Senku use the phone against him? Call the cops and make up a story of abduction...? His age now put Xeno himself in a bit of a predicament... hopefully Senku was not spiteful enough to try and use it. Xeno would just have to make sure Senku realized that the only one who could reverse the effects of the drugs... was  _ Xeno himself _ . And giving Senku his phone would help him reinstall some trust into the boy. 

Xeno placed the phone in front of his assistant, taking his seat on the other side of the table once again. His hands folded, using them as a place to hold his chin as he watched Senku take the smartphone. "What we do now is try to isolate what of the compound is causing this effect in your body and see if there are ways to reverse the effect. The altering I had done to the drug obviously did not do what I had intended..." It was a bit of a lie. The drug could have changed Senku back, sure. All of this was an experiment, in the end. Xeno still could not wait until he could view that video, see Senku's body slowly shrinking...

"Aside from that," Xeno began, standing as he fetched a coffee cup from the kitchen counter, soon beginning to set up the workings of some morning coffee. "I would like to examine your body again, when you are comfortable. You are covered in bruises, we should make sure there is no other damage. Ah - and," Xeno looked up for a moment, getting the dates right in his mind before sending a smile to Senku, "the ultrasound machine should be arriving today."

Despite the fact it was still in the wee hours of the morning in Japan, Senku’s phone pinged with notifications for all the pictures Taiju sent, one or two for each year. Senku scrolled through the pictures for a moment, before sliding the phone over to Xeno. “See which one I look the most like, and I’ll tell you what year it’s from.”

Senku glowered at the idea of further examinations, but he supposed it was for the best. If he did have further injuries, maybe he’d have to go to the hospital, where he could inform the staff of what happened… Although Xeno was too smart for that, he likely already knew that bringing in a child he was too young to have covered in bruises would definitely be a bad look. “…I’m sure you’re going to have a fun time with your lab rat, then.” Senku rolled his eyes at the thought, but figured it was better to know the extent of his changes.

Xeno only chuckled at Senku's words. So sour - he could not blame the boy. Of course he was going to have fun with him. Xeno wanted so bad to tell Senku all the things he had planned to do to him... but it was best to not scare the boy away. 

He took his place back at the table, now with a fresh cup of coffee in hand, sipping it slowly as he took the phone. Just for added measure he locked eyes with Senku while nodding to the coffee machine on the kitchen counter. "Coffee, if you want some. Undoctored, as you can see," he said it while taking another sip. It was best to treat it like a joke - take the severity of Xeno's actions down to a different level. 

Xeno scrolled through the photos slowly. All of them were so cute. His little assistant was always adorable - he would have loved to have met him a few years back. Was he just as ornery then as he was now? Odds are he would have glared with pink cheeks even then if Xeno would dare to call him cute. So many of the images had Senku as some sort of museum, a blue cat-like character grinning in the form of statues or large murals behind him. Xeno glanced up at Senku a few times, comparing to the photos, before sliding the phone back to him. "This one, I believe. You sure do have a lot of pictures with your friend, here." He sipped his coffee quietly as he locked eyes with Senku once more. "Is he more than just a friend?"

Senku reluctantly got up to pour himself a cup of coffee, not adding anything to it before sitting down and taking a sip of it, only to nearly spit it out at Xeno’s question. “Ew, no! Taiju has a girlfriend. He just likes taking pictures.” He narrowed his eyes at the photo, “This one is from my 3rd year of middle school, so I would’ve been 14, since it looks like it was taken in spring.” He picked his phone back up and thanked Taiju for the pictures, then told the oaf to go to sleep.

He sent another text to his roommate, saying that he was staying in Mountain View for the weekend. He didn’t exactly want anyone from the university finding him like this, even if he was able to attend classes, it would still be rather hard to explain.

Xeno couldn't help giving a chuckle. Such a reaction! Did Senku notice the way his cheeks brightened at such a question? So this Taiju boy was not a boyfriend - did Senku ever have a significant other before? Or was he innocent, even in that way? Xeno had to know. 

"With a response like that, I can't help but wonder if you've ever dated," Xeno let out another chuckle as he took another sip from his coffee, dark eyes looking into Senku's red ones, enjoying toying with his assistant. He seemed to be well aware of the predicament he was in. He couldn't just leave. "Tell me, then, have you? Ever had a boyfriend, or a girlfriend? Have you been kissed?" The idea of Senku's mouth being a pure landscape was exhilarating. Xeno had already touched him in new places, taken away a bit of innocence. There was a chance he could do so much more. It didn't matter one bit of Senku's body looked younger - his mind was still that of an adult. And, if anything, it was just making this entire thing a bit more fun.

“Of course not. It’s a trivial waste of time.” Senku paused as he took another drink of his coffee, before quirking an eyebrow at Xeno. “I don’t see how any of this is relevant information, though. You’re pretty terrible at your  _ ‘it’s just for science’ _ excuse.” Senku wasn’t all that savvy with the nuances of other people’s behavior, but even he could pick up on his mentor’s twisted perversion about this whole situation.

“Speaking of… what exactly did you do when I was asleep?” He set his mug down, resting his chin on his hands and staring across the table.

Xeno kept his smile, never faltering as the young boy accused him. He could tell him the truth, but really, trying to touch him while he was so fully passed out wasn't an enjoyable experience in the end. So Xeno only shrugged, "I videotaped you, you can watch the tapes yourself if you wish. There is a small part cut out, when I had to rearrange you back into position. Though..." 

Xeno gave a sigh as he placed his coffee on the table, "I suppose it would be best to clear the air. I am not lying when I say I wish to learn everything I can about this drug. How it works, how to make more, how to cause it to do exactly what I want. You, however." That's when Xeno's smirk began to grow, "I'm quite lucky to have found you. I couldn't have asked for a more fit specimen. Your body seems to be a perfect candidate, and you are clever enough to understand the science behind it all. Of course, the bonus in it all is that I've found myself to be quite fond of playing with your body."

Xeno continued quickly, not letting Senku stew too much on his last words, "you will be compensated, don't worry about that. Your name can appear on the journals, as well as if we can manage to turn this into an FDA approved drug or medical treatment." His smile grew as he leaned forward, resting his chin on his hands and mimicking Senku's own position, "You're my partner in this, Senku. Even if you didn't have much choice in joining. It would be a silly opportunity to turn down. Something like this will do wonders for your career."

Senku’s eyes widened at the implications of some of Xeno’s ‘compliments’, but as he opened his mouth to retort, he found himself being interrupted. Interrupted by some… arguably tempting words. This serum could be a huge leap forward in the medical field, and it would be amazing for his reputation, but… 

“That doesn’t negate the humiliation I’m having to go through.” He finally spoke, swirling around the coffee in his mug. “If we’re really going to be ‘partners’, I’m going to expect that you treat me as some level of equal. I’m not going to be content with being a test subject.”

He thought for a moment, tapping his nails on the tablecloth. “And as my mentor at NASA, I’m going to expect you to provide the excuses to the university for why I’m suddenly not going to classes.” Finally he stood up, making his way over to the fridge, looking around for something to make for a late breakfast. “I’m going to assume I have general free reign, right?”

Xeno was absolutely beaming. Yes -  _ yes _ , he would shower Senku in anything he wanted. NASA was already a well enough paying job - but there was the bonus of NASA sponsoring their employees and any of their scientific endeavors. He had more than enough funds to let Senku live a comfortable life. He would write letters to both Senku's school as well as the NASA center, asking to allow the boy to work from home. 

"You have free reign, yes. Help yourself to anything. Ah, though, I do only have one bed." Xeno's smirk only grew wider when his assistant shot him a stare, "the couch is quite comfortable if that bothers you. We can find a more permanent sleeping space if you wish, but until then, my bed is welcome to you. You've already slept in it once. And in the nude, too."

Senku sneered at the mention of sharing a bed with Xeno, of course he’d be sleeping on the couch. Sure he’d already slept in it, but while drugged, and hopefully Xeno hadn’t slept in there with him… 

A knock at the door was a welcome distraction, Xeno standing at once to direct his attention to the door. It could only be one thing, excitement making his feet move a bit quicker. He wasn't gone for too long, soon coming back to the dining room with a large box and what appeared to be a large metallic briefcase. Xeno placed both of them down near the dining room wall, but took the briefcase into his hand. The box was full of more... testing equipment that Senku didn't need to see just yet. The briefcase, however... 

Forcing the thought from his mind, Senku busied himself with making a meal. It was nearly noon, so he supposed it counted as lunch rather than breakfast, but it didn’t particularly matter. A meal was a meal. It didn’t take long for him to sit down at the table with a grilled cheese sandwich, just as Xeno came in with what he assumed was just delivered.

Xeno laid the briefcase onto the dining room table, carefully opening it. It opened much like a laptop, showing a screen on top with a keyboard and other controls on the bottom. At its side it held a compartment with a few different attachments. It was obvious to anyone who had ever stepped inside a radiology room - or really, anyone who had ever seen something similar in media. An ultrasound machine. A portable version, at least. 

Xeno shined a smile to Senku, "it seems our testing can resume whenever you are ready."

The ultrasound was expected, Xeno had mentioned it earlier. It would be interesting to know the full extent of Senku’s transformation, if he had a functioning womb and ovaries it would be almost a miracle in the field of reproductive medicine.

Xeno sat back at the table, legs crossing as he pulled a small instruction manual from the ultrasound kit. It would be his first time using one of these, but with a bit of reading he was sure he could at least understand it enough to find hints of ovaries or a womb. Senku seemed busy with his meal, though Xeno had hoped he was able to watch the boy move and cook around the kitchen. Senku was already a petite boy. But now he was just tall enough to work on the kitchen counter. To get to the higher shelves he'd have to use a stool, or ask for help. Xeno could invest in a simple kitchen stool... but having his assistant ask him for help to grab high things just sounded too amusing. Though, he was sure Senku would be the type to drag a chair over before actually asking for help. 

“What’s in the box?” Senku quirked an eyebrow, mumbling through a mouthful of sandwich and glancing suspiciously at the box by the wall.

Xeno gave a small hum to Senku's question. He would rather Senku not go through the box. Seeing the questionable toys that had been delivered would definitely support Senku's theory for Xeno's intentions being far from scientific. Even still, he knew Senku required an answer. "I believe I had told you the other day that I had meant to buy a few things. A speculum, gloves, lubrication, a few other things to assist us." A thought entered Xeno's mind then, his finger and thumb prodding at his chin as he processed it, "your body has gone through such a drastic change. Much of our recordings from our previous tests will now be off. I am sure your vaginal canal is much smaller. But," he shot a smile back to Senku, "these are things we can worry about after your lunch."

Senku nodded as Xeno listed his purchases, getting up once more to pour himself another coffee. Thankfully his tastebuds hadn’t regressed, he had hated anything bitter when he was younger, much preferring energy drinks that tasted more like a color than any supposed fruit. 

It would take a while to get used to his body again. He had forgotten just how small he was, considering his biggest growth spurt happened at sixteen. The mug felt strangely big in his hands, he had to stand on his tiptoes to reach the cupboards, his feet dangled just barely off the floor. Xeno’s t-shirt, which likely would have fit him before, hung comically big on his frame.

“Afterwards, we can worry about clothes. I’d rather go and pick things out myself, but I should be a men’s extra small.” He chose to leave off his size in children’s clothing, not wanting to give Xeno any ideas.

_ A men's extra small. _ Xeno watched as Senku moved. A men's extra small would hang loosely on him. Perhaps measurements were in order. Even that idea felt exciting, running a fabric measuring tape against Senku's body, finding out exactly how tall he was, the diameter of his waist and chest. But - he would humor the boy for now. Maybe sneak in a single childish outfit, just to see if Senku would take the bait... 

Xeno's mind shot back to the images Senku had shown him on his phone. A few were at the park with his friend, but he remembered some others - perhaps it was a museum...? A blue-skinned cartoon character was in the background, one with a round and happy face. Some internet searches of Japanese cartoons and mascots would most likely bring up who the character was. Senku seemed quite happy in front of those displays. A shirt or two could be cute. Though, Xeno's mind began to wander at what other sorts of clothing he could find to dress Senku in... 

Senku quickly finished his lunch, he had been a lot hungrier than he realized. It made sense he supposed, he hadn’t eaten for well over 12 hours, and his body surely was using a lot of energy as he slept. He grabbed an apple from the center of the table and bit into that as well, careful not to let any of the juice slide down his chin. He didn’t want to fuel any strange fantasies on Xeno’s part.

"Right," Xeno cleared his throat - no time for such thoughts, work needed to be done. He closed the portable ultrasound machine, making sure to be careful as he moved with it. This model alone cost near twenty five grand, which was why some companies rented them out in the first place. Not many people had that sort of money laying around - even Xeno couldn't see himself spending over twenty grand on an item he would use once. He looked to Senku with a kind smile, "I will be doing some research of my own, so that we can properly use this. When you are ready, you can meet me in the bedroom. I do need you laying down, after all." With that, Xeno gave Senku a slow nod before walking off towards the bedroom.

“Right.” Senku gave his apparent caretaker a small wave as he left the room, finishing off his apple and cup of coffee before going off to explore the apartment while Xeno set everything up. He browsed through the bookshelves in the living room, pulling down anything he thought may be interesting, familiarized himself with the layout of the house, and made an attempt to enter Xeno’s office, which was unfortunately locked. He had found himself disappointed with the strange normalcy of the home, as well as with the lack of game systems. He’d have to ask his roommate to send his Switch down somehow. 

Finally, once he had bored himself, he went back into the bedroom to go through with another humiliating examination.

Xeno had a few different things laid out on the bed. The ultrasound machine itself, now turned on and showing a blank gray screen. The user manual, open to a random page. And Xeno, crisscrossed on one side of the bed, face brightened by the laptop on his lap. He did not notice Senku walk in, eyes scanning the screen. The user manual only offered basic instructions how to use and care for the machine. All useful things to know, but not useful in finding what Xeno needed to find within Senku's body. The internet, however, provided a lot more information, as well as how and where to find the organs that Xeno was looking for, as well as examples of the images himself. 

Would it be perfect? Far from it. But it would be hard to get Senku a proper appointment with a real radiologist without doctors being very shocked at the fact that this young man, with female genitalia, had medical records that showed the age of an adult. So this would have to do, for now. 

It was only when Senku came near the bed that Xeno finally noticed him, looking over with wide eyes. "Ah - there you are," he patted at the bed, flashing a smile. "This shouldn't take too long. Lay back, and raise your shirt, please."

Senku placed his small stack of books on the side table before crawling onto the bed, before laying down, raising his shirt above his stomach and grabbing a book off the top of his stack. There was no point in being difficult, not at this point. It would be valuable information to have, if only so he could prepare for a possible menstrual cycle.

He tensed a little as the cold gel was applied to his stomach, as well as the wand moving over his skin, but he could ignore the strange sensations well enough by focusing on his book, a history of Soviet animal cosmonauts. It wasn’t relevant knowledge at all, but it was interesting at least.

"I should warn you," Xeno began, kneeling closer to Senku as he slowly pressed the sensor to his lower abdomen, spreading the cold gel, "this is not my area of expertise, though I do understand the basics." Xeno reached over, pressing at a few keys to bring up the proper screens. "We should be able to determine if you are...  _ fully developed _ , at least. And what measures to take, if you are."

A light press did nothing - it took pressure, pressing hard at Senku's lower abdomen. But, sure enough, the screen started to show confusing looking objects. Senku's bladder was easy to find - and it would lead Xeno to the organs he wished to see. Of course, they would be much easier to view with an internal ultrasound... but the rental ultrasound did not come with the wand to conduct a proper internal pelvic exam. So this would have to do. 

"See, here," Xeno slowly traced out a few images with his fingers, looking up to his assistant, "you did in fact grow a uterus as well. My fingers did not hit the uterine wall when I examined you before, though that is probably different now," Xeno had to keep his excitement inside, the idea of slowly opening Senku up again... he cleared his throat as he continued, sliding the device slowly to the side, still pressing hard, "and here - ovaries, you can make them out," he traced them again.  _ Fascinating _ . He really did have a full change... 

Xeno removed the sensor from Senku, the screen turning black as he did so. "Those of your age would have had their first menstruation cycle by now," he soon sighed, cleaning off the censor with a small cloth, "I never took much interest into learning about such things, though I suppose looking into it now won't hurt." He placed the rag on Senku's stomach, allowing him to clean himself up, standing up from the bed.

Senku was surprised to hear of his full transformation, but nodded slowly. “I know a little, since one of my friends has a particularly bad menstruation cycle. I’ll be able to deal with it.” He paused for a moment as he cleaned himself up, before looking back up at Xeno. “This is an amazing development, though. Assuming there’s no ill effects later on, of course.”

Once he was clean, he lowered his shirt back down. “I’m going to have my roommate bring down some of my things today, assuming we don’t have any other tests. I’ll just have him drop them at the front desk, I don’t want him seeing me like this…” He glared down at his body, still upset with his current predicament.

Xeno nodded slowly. Senku didn't seem too bothered by the idea of menstruation... but there was a chance he would think differently soon once the pain started. He would be sure to pick up some more painkillers as well. 

A few other thoughts flickered through Xeno's mind. With an intact womb and ovaries, Xeno could not be as...  _ careless  _ as he had hoped to be with Senku's body. Certain methods of protection would need to be thought about. 

"Right," Xeno then said, walking to his closet and bringing out a jacket. "Do be careful, we do not need anyone making a big deal out of this. You have free reign of the house, as before. Please try to not set the place on fire." Xeno flattened the jacket out once it was on him. He had fallen asleep on his desk that morning so he was far from his usual put-together self, but this would do. He shot a small smile to his assistant before walking out of the bedroom door, "if you're good, maybe I'll buy you a treat." 

He knew the comment would annoy Senku, which was the exact reason he had said it, turning his back to the boy and walking from the room. It was good he needed to pick up a few groceries, anyway. He would buy an outfit or two for Senku's new body, and perhaps a few other things... Once Senku had those, then the boy could go out and shop for his own clothing.

Senku rolled his eyes at Xeno’s teases, he was still an adult after all. Of course he could be responsible, he’d probably been more mature at 14 than Xeno was at 20. 

Once he was alone, Senku texted his roommate with his location and the items he needed, things like toiletries, chargers, textbooks, his video games, things he deemed necessities. Once he’d received confirmation, he made his way to the living room to continue reading his book. 

It didn’t take him long to finish it though, it was a fairly short read. Rather than grab the next one in the stack, Senku made his way to the kitchen to inspect the box that had arrived earlier. Xeno didn’t seem to want to reveal what was inside, but his curiosity was piqued. Surely if it were nothing worth hiding, he wouldn’t have cared, right?

Senku carefully peeled up the tape, making sure it kept its stick so he could reseal the package. On top was what Xeno claimed: a speculum, a box of sterile rubber gloves, a bottle of lubrication… that didn’t seem to be all that was in the box, though. Underneath a layer of brown paper was some odd boxes, featuring pictures of silicone toys in varying colors and sizes. Senku’s cheeks flushed bright red and he quickly put the toys back in the box and covered them with the paper, before sealing the box back up. If nothing else, that certainly confirmed the doctor’s intentions here. He again debated telling someone what was happening, but knew that if Xeno was somehow apprehended, nearly all hope of returning to his natural state was lost. 

He’d just have to avoid any advances until they figured all this out, that’s all.


	4. Experiment 04

Xeno had never been big on shopping. It was a grueling task - usually he set up deliveries of both items and groceries to be sent right to his door. Not a cheap service at all, but Xeno was just too busy to waste time browsing shelves among crowds of people. 

But there was no time to wait for deliveries today. The local department store had all the things he needed. Xeno worried first about restocking household items that he needed, filling the small basket he held on his arm. The true intention of his outing, however, was in the clothing department. A men's size small - still probably a bit too big for Senku, but Xeno was tasked with doing what Senku asked. _ For now. _ It was best to keep him happy. A happy test subject is a willing one, after all. 

Xeno had always seen his assistant in lab clothing, so the choices in colors were a bit overwhelming. Xeno stuck to neutral tones, folding a couple shirts and pants into the small basket, wondering if he should have gotten a cart instead. Was Senku one for wearing shorts...? Xeno had no real idea, but the idea of seeing slender legs walk around the apartment was tempting enough to also fill the basket with a few pairs. 

Of course, Xeno could not stop only with pants and shirts. He sighed softly as he realized how many other things he would need to pick up. A pack of socks also entered the basket, as well as simple sandals that seemed about the right size - Senku could find proper fitting shoes once he could shop for himself. And then - just one more thing needed.

Xeno stood in the small aisle that held an array of different types of underwear. There were many sizes - he tried to think what would fit Senku's waist and legs. He had not yet really touched this new body of his, so it was hard to guess. What size was he, when Xeno was that age...? Xeno slowly reached out towards a pair of boxers... before stopping, his eyes falling on something else, a few sections over. Small briefs, a pack of six, all decorated in different prints of space and rockets. A small smirk pulled at his lips. Senku would have to wear some sort of undergarment - and if these were the only ones he had around... 

Xeno grabbed the pack, placing them into the overflowing basket. 

* * *

Senku had returned to his spot on the couch, moving on to another book about material sciences, and trying to push Xeno’s purchases from his head. It wasn’t too long before the sound of the door alerted him to the return of his mentor, and the arrival of clothes that weren’t too big to wear. 

When Xeno walked in through the front door of his apartment he was happy to see that Senku was  _ still _ there. A part of him had feared that the boy would run as soon as he got the chance, but Senku was too smart for that. He must have known, deep down, that the only one that could return Senku to his previous state was Xeno himself. He shared a warm smile with the boy, walking over to place two of the grocery bags beside him on the couch before then walking to the kitchen to begin sorting through the rest of the groceries. "I hope everything fits all right. If not, they should fit well enough to at least get you out on your own so that you can try on things yourself."

Senku dug through the bags, thankful to not have to wear Xeno’s clothing anymore. Even if it was for less than a day, it was more than humiliating. He quickly pulled out a white t-shirt, a pair of jeans, and… perhaps the most childish underwear he’d had to wear in ten years. “Cute. Very cute.” Senku rolled his eyes as he stood up, then headed to the bathroom to change. He could get some plain undergarments when he went out by himself.

The annoyed look that Xeno got made the purchase very worth it. He only smiled back, watching as Senku took the handful of clothing into the bathroom. As soon as Senku got to a store himself he would most likely change his wardrobe to something more fitting for himself... but until then, he would have to wear the cute childish underwear. Xeno gave a sigh, sitting on the couch, a new cup of coffee warming his palms. The little rocket and star prints would be so nice to slowly trace while on him. Lick at Senku's most private areas through the fabric, both his own saliva and Senku's wetness causing the fabric to grow dark and near see-through. It would be so easy, once soaked, to...

No, no, Xeno softly cleared his throat, sipping at the coffee. It would do no good to fantasize now and only cause himself to become bothered and needy. The next goal was simply encouraging Senku to allow more touching, 'testing', even if the boy most likely knew Xeno had ulterior motives. Xeno only wanted to make Senku feel good, in the end. His body seemed mature enough to experience orgasms. If Xeno could just cause Senku to become completely addicted to the desire to be touched and, just maybe, even fucked endlessly... Yes, then, this entire experiment would be a success. And that didn't even include if they were able to find out the full nature of the mystery serum. 

Once alone in the bathroom, Senku decided to take a shower, washing off the dried sweat from the night before and the remains of the ultrasound gel, and pulling the last of the pomade from his hair. He stepped out of the shower and quickly dried himself off and got dressed, before catching a glimpse of himself in the mirror.

It was still a shock, seeing his own round eyes and cheeks still soft with baby fat. His hair stuck up in odd shapes, he’d probably have to brush it later, but he supposed he could let it hang down for a while. It made him a little less recognizable if he did that, bright green ends aside. 

Finally he came out of the bathroom, tossing his dirty clothes into Xeno’s laundry basket, before wandering back into the kitchen.

Xeno shared his usual soft smile, placing his mug down onto the coffee table. "Everything seems to fit decently, I presume?"

Senku nodded as he sat down on the couch, opposite from Xeno. “They’re a little big, but I won’t be going anywhere where it would matter.” He picked up his book, turning his attention back to it. Some of the properties described in it were experiments he had done in the past, but others were new. 

“My roommate is going to bring my stuff down tomorrow, I told him to leave it with the front desk.” He checked his phone to confirm the time, “5pm tomorrow. I’m going to assume you’ll be home, right? What’s your schedule even going to look like now? I’m sure mine will be pretty bare.”

Xeno gave a small tut to his tongue, tsking the young boy, "is that animosity I hear?" he began to tease, though knowing full well that Senku probably held a number of grudges at this point. "I will be home, yes. My schedule has always been a little up-in-the-air. I have a lot of vacation time as well." Xeno had already thought it through. It would not hurt him to take some time away from work. He rarely took vacations, so he had over a month of paid time off racked up by now. Not only that, but it would be simple to apply for a short leave of absence. However - such a thing would mean getting a little too far behind in his work... 

Xeno crossed his legs slowly, fingers tapping on his knee, "my plan, right now, is to take a majority of my work at home. Paperwork and anything simply needing a computer I can complete here with no issue. This means I will only need to attend the labs once or twice a week." His work would slow immensely... but he would at least stay up to par, this way. The extra time at home, however.... 

He turned his body to face Senku, arm now resting on the back of the couch, his almost-too-warm smile spreading on his lips again. "This means we can spend more time together." He waited until Senku stared back at him before continuing his words, "to work on getting your body back to normal, of course."

Senku listened absently to Xeno's tentative plan, though he kept most of his attention on the book in front of him. That is, at least until he heard Xeno's purposefully overly-sultry tone. He stared for a moment in bewilderment until the statement was continued, and he rolled his eyes. "Right, right, pervert." He leaned back against the arm of the couch, bringing his knees up to keep himself small.

That little move - the short and quick movements of Senku's legs slowly closing in close to himself. Xeno was almost worried with how much such a simple move had excited him. Such a small and quick protective barrier against himself and Xeno... But Senku must have known how easy it could be. To pin his back to the couch and force those slender legs down. Senku needed to be made aware of this as soon as possible - that there would be...  _ stipulations  _ to their testing. If Xeno was going to work on this mysterious compound with him, then Senku would have to be prepared for tests of all kinds.

After a few minutes, he glanced over at Xeno once more. "If we have extra time then, could we take a day to go up to San Francisco? I'll probably have better luck finding clothes that fit me properly in Japantown, if I can find somewhere that sells imports." He had been to the Japantown Center on recommendation of one of his classmates, and while he wasn't too impressed with the stores, they'd at least have smaller sizes available for him to try on.

"We can," Xeno answered, giving a nod. "We can go wherever you wish. In fact," Xeno stood then, walking around the back of the couch, "for your time being here, you can consider my money your money, within reason. Being stuck here, after all, would be rather boring without some compensation." Xeno was behind Senku now, leaning forward as he placed both of his hands on the boy's shoulders, looming over him, "however, Senku. I believe you have become well aware of what I require from you," one of Xeno's hands left Senku's shoulder, only to move to the boy's chin as he forced him to look up and into Xeno's eyes, "you'll be my good little test subject, won't you? We have further tests to do, before the day is done."

Senku only half-listened to Xeno’s words, barely noticing as the older man got up and began stalking behind the couch. He was only brought out of his haze by the touch to his shoulder, and the grip on his chin. His crimson eyes widened as he stared up at Xeno, and his hands fell slack with his book dropping into his lap.

It only took a moment before the daze was broken, though. He pursed his lips and grabbed Xeno’s wrist, tugging his hand away from his face. “I’ll be good for tests that are relevant, but don’t think money is just going to make me bend over backwards for you.” His brows lowered into a glare, and he picked his book back up when Xeno withdrew his hand.

A grin pulled on Xeno's lips.  _ Bend over backward for him _ . He wanted to poke fun at the words. Senku would bend over backwards, eventually. Perhaps not by tonight, but soon. "Right, then," he began, walking towards the box that sat near the kitchen wall, picking it up. The contents inside jostled as he stood. After tonight, there were more things on Xeno's mind that he could purchase... He was sure that within a week, he would have spent more than a few paychecks solely on this boy alone. 

He made his way back over to Senku, holding the brown box a bit higher, bringing Senku's attention to it. "Then, humor me for now. Let us get these  _ 'relevant _ ' tests done and over with, so you can enjoy the rest of your night. I'll even have dinner delivered, your pick." There was a chance he was spoiling the boy a bit too much already... but the words just fell from his mouth. Whatever Senku wanted, Xeno would give him.

Senku realized a little too late that his word choice was less than ideal, but correcting himself now would just serve to make it worse. For now he ignored Xeno’s grin and kept reading his book, only looking up at the noise of the box he had opened earlier. Good, the tape hadn’t come undone, so he could still feign a little bit of innocence.

He nodded and stood up silently, bringing his books with him into the bedroom to keep himself entertained. Hopefully Xeno was, in fact, only going to keep it to the relevant tests, instead of using the toys hidden at the bottom of the box, but Senku was sure that he would somehow try and reason his way into using them on Senku’s new parts. He had to test the limits of them or some other thinly veiled excuse.

Senku had followed so willingly - perhaps just with the desire to get this done and over with. That was fine. There were legitimate things that Xeno wished to know about Senku's new body. He only hoped that he could make Senku begin to feel good before those experiments finished, and that the pleasured mindset would let Xeno continue on to more...  _ personal  _ experiments. Though, it did not really matter. Xeno intended to see Senku's new body experience an orgasm whether he was willing or not. A willing participant was just...  _ easier _ . 

Xeno turned the light on as he entered his room, flattening out the bed sheets before patting on a spot and signaling Senku to sit there. He placed the box onto the bed, pulling up at the tape and carefully digging inside to only take out the things he needed for now. Lube, gloves... and, "ah, here we are," Xeno held up the speculum, admiring it's simple design. "A good thing I bought the smaller one, in the end." He shot a smile to Senku, "if you could undress, we could begin. Unless you need help with such a thing, now."

“I’d ask if you have ever interacted with a teenager, but I’m going to assume it’s better if you haven’t.” Senku sat down and removed his bottoms, then rested back against the pillows and hid his face behind his book. “Besides, my mind is still the same.”

There wasn’t a drastic change to his body, aside from being generally smaller and more slight. Before he had a few patches of thin blond body hair, which had disappeared when he regressed. Senku had been a late bloomer, especially when compared to Taiju, the oaf had to start shaving a mustache at eleven years old. 

He wasn’t too sure what to expect with this examination, aside from physical and mental discomfort, but he was determined to remain stoic throughout the procedure. He didn’t want to fuel any of Xeno’s fantasies with accidental noises.

Xeno chuckled softly, now placing the box onto the floor. "If you are trying to insinuate that I've slept with a minor then, no, of course not." Xeno sat on the bed then, positioning himself near Senku's slender legs. "But, as you say, you are not technically a child." Xeno's hands were careful, only soft touches coaxing Senku's legs to bend and become wider, revealing his very new sex. 

Senku wasn’t sure how he felt about the gentleness behind Xeno’s touches. On one hand, he appreciated how careful the doctor was being, but of course he had ulterior motives, and it would be quite easy to just ask Senku to move his legs on his own.

Xeno did his best to hide any hunger appearing on his face, happy for now that Senku's eyes were focused on the book in front of him. His desire to run his bare fingers across the small slit was almost too strong, but Xeno held himself back, taking the small box of gloves and tearing into the box. Once the gloves were on, the lube came next, a generous amount onto Xeno's first two fingers. 

"It'll be cold, now," he said, voice low, eyes focused on Senku's body as his other hand slowly spread at Senku's folds, revealing his most sensitive parts. With little hesitation, Xeno ran his lubed fingers around Senku's entrance, already noting one thing of importance, "your hymen doesn't seem to have repaired itself, despite the regression and change." This made things a bit easier, allowing Xeno to slowly insert a single finger into the boy, only daring to go up to the first knuckle for now. "I will ensure you are properly lubed... before inserting the tool. For comfort, of course."

Senku was grateful for the book to distract himself, his breath hitching at the sudden sensation against his slit. It was certainly cold, along with the embarrassment that accompanied it. “Well, it doesn’t serve any proper purpose, does it?” He tried to keep his voice from quivering, from what he couldn’t tell. Cold, humiliation, some kind of sick arousal… it was no use to think about it now, he should just focus on the words in front of his face. Primitive material science, it was interesting stuff. Far more interesting than what was happening between his legs.

Xeno gave a soft hum, his finger moving in easy circles, coating Senku's inner walls. "The hymen? It's theorized that it keeps germs and bacteria out of adolescent wombs, but," Xeno's finger slowly started to delve deeper then, feeling Senku's body tentatively clench around him, "that's only a theory and nothing more. As for you, however, there is no longer any proper purpose." In fact, it would only get in the way now... though, Xeno had a small, quick wonder, how it would have felt to break past Senku's barriers with something more... personal than just his fingers... but Xeno pushed the thought from his head, for now. 

Senku steadied his breathing and closed his eyes, brows knitted together as he focused on anything other than the finger probing along his walls. His roommate would bring his personal items tomorrow, maybe the day after they could go to Japantown. There were a few shops Senku knew of, but he’d have to look that up later.

Senku was properly lubed by now. Xeno couldn't keep twisting and having his fun without Senku accusing him of stalling. His finger slowly fell from Senku's body, missing the warmth already, quickly picking up the speculum. He only had one real goal here, viewing Senku's most...  _ inner  _ parts. Just to see if he was healthy, if he was intact, if what Xeno saw would match the images he had spent all night and morning looking at. 

More lube - now coating the metal tool. "If you feel discomfort, please let me know," Xeno began, his tone earnest. He did not want to harm Senku, truly he didn't. A gloved hand spread Senku's folds wide once more, the cold bit of metal slowly inserting into his sex, the thickness definitely wider than Xeno's single digit. Xeno wasn't able to control the way he licked at his lips, watching Senku's body stretch as the piece moved deeper.

Senku released a breath he didn’t know he was holding, relieved that the finger was gone. Of course, it was replaced with a far more uncomfortable, freezing cold piece of metal, spreading his walls even further. He pursed his lips together, continuing to forcibly distract himself. Maybe he could get Xeno to take him to a bookstore, he could read perfectly well in English, but it would be nice to have a break from his second language, and perhaps fiction would be a bit more engaging than various scientific texts.

Xeno's eyes shot up to Senku's face, watching his furrowed brows, closed eyes, not even reading the book anymore. So it was too much already? Of course, Xeno was making this a lot more sexual than it needed to be... A normal pap-smear would most likely be finished by now, a simple procedure, in and out. But Senku didn't know this, so Xeno took his dear sweet time in slowly inserting the piece of metal. Once a good way inside, it only took a small twist of the outer handles to do what the tool was really meant for - widening even more, slowly opening Senku as far as his small body would allow. 

Xeno, however, was not in the best position for such a test. It would have been better with Senku laying across the table, Xeno sitting down low. But the bed was comfortable. Xeno reached towards the other side of the bed, grabbing a thick pillow, bringing it over to the boy's waist. "I'm going to lift your waist, now," Xeno warned, knowing Senku's eyes were still screwed shut, and did not want to risk him squirming with the tool so deeply rooted into him. 

Once Senku's hips were lifted, Xeno slid the pillow beneath, the angle causing Senku's body to curl slightly inward, his sex now at a much more...  _ observable  _ position. It was to be expected - Senku's inner walls dark with shadows. But such a thing was remedied by the shine of Xeno's cell phone flashlight, using the bright beam to really, really examine the boy beneath him.

"Fascinating", Xeno said, feeling nearly breathless. No deformities, no mutations. A perfect, light pink color. Entirely intact. Yes, this definitely changed a few things. More protection. More research on how to prevent...  _ certain  _ outcomes. But to really be able to see it, not just on a screen, or on the ultrasound machine. For just a moment, Xeno forgot where he was, who he was staring at, only knowing full well that this serum... if they could really recreate it and produce more of it, and perhaps even a version for the opposite sex... it would absolutely change the medical world.

Senku made a conscious effort to even out his breathing, not wanting to let out any noises. He was grateful for the warnings Xeno gave, and his interest was piqued at Xeno’s breathy whisper. “I… I take it nothing is wrong?” He still didn’t move, not wanting to jostle anything around, but he hoped that everything was alright. If the serum had worked perfectly, he wouldn’t have gone through all of this for nothing.

"Yes yes," Xeno couldn't pull his eyes away, "nothing is wrong, not at all. In fact, everything seems absolutely perfect." Xeno explained then - perhaps in too great of detail, everything he could see. The glistening walls of his canal, the uterine wall, the small opening of the organ, not a single blemish or deformity. A complete change, down to every single cell. "We'll be able to determine if they are functioning organs if you do, in fact, have a menstrual cycle. But we can assume that if you are able to menstruate, then you'd be able to carry a child, perhaps even to term..." Xeno knew there was a lot more to it than just the uterus and ovaries. Perhaps those changed by this serum would need to take certain supplemental medicines. But just this alone... the scientist that had left the experiment in a box in the storage rooms had missed out on quite the chance. 

Senku sneered at the thought of being fertile like this, and he scoffed. “I’m not going to test that for you. You can take the serum yourself if you want to make sure.” He didn’t want to admit not just how much the idea disgusted him, but terrified him. He’d have to make sure he somehow got on birth control, otherwise he didn’t quite trust Xeno to control himself. Though, the doctor didn’t seem to be at the point where he wanted a child anyway. Hopefully Senku’s regression would be enough for him.

"Even here," Xeno said as he softly twisted the speculum, the gaps in the metal now allowing Xeno to insert his finger and rub against the upper walls of Senku's sex, pressing hard until he found the spot that caused his assistant's knees to jerk slightly. "And... here, as well," his other hand moved forward, thumb pad pressing against Senku's clit, "the transformation has even grown all the perfect nerve endings... Truly, absolutely perfect..."

It took more control than Senku expected to not react to Xeno’s likely intentionally pleasurable touches, not wanting to risk jostling any equipment or letting any embarrassing noises slip through. “I’m sure it’s a little early to start manufacturing more, but it might be a good idea to think about how we would go about it, if the change is so complete… there’s likely a decent market for it.”

Senku was doing his best to not react. Of course he was - this part was purely scientific. Xeno could try and play it off, tell Senku that he wishes to bring the boy to orgasm once more, to see if the timing or sensitivity has changed. But Senku was too smart to fall for such things anymore... But that also did not mean that Xeno had to stop, not just yet. 

"Yes, our next step will be not only finding a way to recreate the compound, but also a reverse form, to change the female sex to a male one..." It would take a lot of restless nights to perfect it... but the results would be worth it, in the end. 

Senku was all for a reversal serum, he would love to have his normal body back. Well, relatively normal. Xeno hadn’t mentioned anything about returning him to his proper age yet. 

Xeno was slow as he pulled the speculum from Senku's body, keeping it at its widest form as he did so. Once out, Xeno did not hesitate at all to replace the tool with two of his own fingers, though he was quick to give a reason for the intrusion, "your canal has definitely shrunk. Not by too much, perhaps a few centimeters. Then again, the canal lengthens when sexually aroused..." Senku's mind may have been distracted, but his body was not. It wasn't much, far from the first time Xeno had touched the boy's body, but enough to be seen. The swelling of his clit, or just the way Senku's walls clenched around his fingers, dripping already with their own lubrication. 

The moment he felt Xeno’s fingers delving into his heat though, Senku opened his mouth to berate him, only to be interrupted. Right, this was still an _ ‘examination’, _ his mentor was at least still pretending. “A-and I’m sure you want to test that out…” He mumbled under his breath, laying his head against the pillows.

"Senku..." Xeno's voice was soft, finding himself enamored with the sight in front of him. "You've been such a willing participant. Allow me, please," his thumb pressed once more at Senku's clit, feeling it throb against his finger, even through his gloves. Xeno's face moved down, his lips softly grazing the skin of Senku's inner thigh, "to reward you for your services to me."

Senku held in a whimper at Xeno’s deliberate movements, before releasing a small sigh. “Y-you’re not going to take ’no’ for an answer, are you?”

Xeno's lips still laid against Senku's thigh, a smirk soon being pressed against them. "You  _ are  _ such a clever boy," he whispered into Senku's skin. Xeno had been prepared to proceed further, even if Senku had tried to deny him. But this made things much easier, seeing as Xeno's limbs would have more freedom when not having to hold a struggling body down. His gloves came off - a small signal now that the real experiment was over. Everything from here on out was not needed for mass production of the serum. This was purely for Xeno's own desire to learn every inch of Senku's new body. 

Senku tensed and covered his face with his book. Xeno was teasing, of course he was. He had been teasing since Senku had shown up that godforsaken morning, and it was all finally coming to a culmination for him. He wanted so badly to hear every noise, feel every movement, and Senku wasn’t going to give it to him so easily.

He moved his face down lower, knowing full well his actions would come at a great surprise, bare thumbs now spreading Senku's folds wide. Xeno had been thinking about this the day he saw the change in his assistant, but having the chance right in front of him was causing Xeno's own excitement to feel confined and desperate in his pants. Even before tricking his intern to drink the serum, Xeno held a great fondness for him. Such a smart mind, bright, yet so innocent in all the right places. Oh, how he would dream of corrupting such a pure mind... 

And now, here Senku was, smaller than before, more vulnerable than ever, knees bent and hanging wide, spread so deliciously wide, all for him, and a bit for science as well. Xeno's face sunk deeper, eyes closing with delight as his tongue slowly traveled up Senku's wet slit, sinking only for a moment into his entrance before traveling higher, landing on his clit, his entire mouth closing around the swollen mound.

Senku held his breath, toes curling in anticipation when his lips were spread. It was agonizingly slow, and Senku at last broke his silence with a shaky sigh as Xeno’s tongue slowly traveled up his slit, and his breath hitching at the sucking against his clit. His legs closed a little bit, squeezing gently before quickly widening again.

Xeno knew he needed to take it slow. To really, really make Senku's body yearn for it, desire it... it probably wasn't possible to get him to beg yet, but Xeno could still lay all the groundwork. Senku wasn't pulling away or denying Xeno access, and that was all the permission he needed. Xeno's tongue continuously flicked against the swollen clit, going until he could hear Senku's breathing begin to hitch before softly suckling once more. Never enough to bring him close to orgasm, only enough to tease. 

His hand slowly joined in, two now bare fingers teasing around Senku's entrance. Even with his entrance, Xeno moved at a leisurely pace, delving in with gentle pressure. The speculum had done a good job at stretching Senku's walls, making it so the fingers had no issue at all as they slowly began to thrust into Senku's body, in and out, leftover lube and Senku's own juices making erotic sounds with each movement. 

Xeno was adventerous with his tongue, leaving the clit to lick around Senku's folds, his thighs, teeth grazing across sensitive skin before moving lower to let his tongue delve deep into Senku's sex along with his moving fingers. He curled the fingers when he could, pressing hard into Senku's upper walls, eager to find the bundle of nerves that could send his assistant barreling closer to the edge. 

Minutes had passed - how many, Xeno was not sure, losing himself in the rhythm of moving his tongue and fingers fast against Senku's heat, before slowing to an agonizingly slow pace. He kept it up until he could hear the lowest of whimpers come from his very stubborn assistant, looking up now to star at his flushed face, "are you close, my dear?" His face pulled away from Senku's legs, beginning to smirk, his fingers never stopping their movements, "do you wish for me to bring you to your peak?"

Senku kept his breathing steady, his eyes fluttering shut at the gentle attention. He could berate Xeno for his perversion, his eagerness to pleasure his assistant like this, for forming attraction to a mid-pubescent body, or keeping a preexisting attraction despite it. But he wasn’t about to distract the tongue between his legs, drawing soft breaths and near-inaudible whimpers from his mouth.

The fingers added another dimension, even if he had already come on Xeno’s fingers before, there was no trace of pain this time, considering his body had gotten used to the speculum. Each movement caused Senku to grip at the cover of his book, not wanting them to instead fly to Xeno’s hair. 

At least, not until he pulled away, speaking in a teasing voice. Senku let out an impatient grunt and pulled Xeno’s face back in between his legs, his fingers twining through his hair and his thighs squeezing around his head. “Shut up…”

Xeno... did not expect  _ that _ . In fact, the smallest of groans left his own throat, gladly obeying the grasping hand in his hair, his mouth surrounding Senku's clit once more as he began to suckle and flick his tongue against the mound in a quick fashion. His fingers continued as well, the sounds of wet slapping skin now filling the room. Senku's grip in his hair alone could have caused Xeno to orgasm on the spot, if it were not for his own control. Senku was such a stubborn boy... but right now, right here... if Xeno's mouth was not so busy, he would have enjoyed telling Senku how needy he was being, or even toss out a few degrading names, just to see his reaction... 

It didn't take long at all for Xeno to finally feel it once more - the sudden clasping of Senku's innermost walls, the rocking of his hips. Xeno did not stop his motions, though he did slow them, allowing Senku to lose himself in his peak.

Senku quickly neared his edge again, spurred on by Xeno’s apparent increased fervor. Maybe he was a masochist, Senku would have to test that, it would at least give him some leverage against him. That didn’t matter though, not right now, not when all his muscles were tensing and he let out a high keen as he came, counting the seconds that it lasted. _ Twenty seven _ , he couldn’t remember how long his first orgasm the other day had lasted, he’d have to check his notes.

When his muscles finally relaxed, he pushed Xeno’s face back with a small grunt. “H-happy now?” He shot a glare down as he groped around for his underwear, wanting to cover himself up as soon as possible.

Xeno kept his smile, allowing Senku to push him away. He had gotten his way, pushing too far now would only upset the boy. With the back of his hand, Xeno wiped away at the glistening wetness on his mouth and chin, making sure to lick at his lips before wiping them as well. "Very pleased, actually. I learned a lot of things about you, Senku, in those few minutes." 

With that, Xeno began to remove himself from the bed... though he stopped, only for a moment, his body leaning close to Senku, looming over him entirely as his face approached the boy's neck. He did not kiss - he did not even allow his lips to graze Senku's skin. Instead, he spoke low, "this coming weekend, we should go out somewhere. I'd hate for you to be cooped up here forever. I'll even let you pick where we go." Xeno backed off then, his usual warm smile in place, now turning from Senku as he made his way to the bedroom door. "You may do whatever you wish for the night. The linen closet has extra pillows and blankets, feel free to treat the living room as your own, since you refuse to use the bed. I'll be taking a shower." 

Xeno did not wait for a response, heading straight for the nearby bathroom and shutting himself inside. It allowed him to take a deep breath, back braced against the door. His breath felt heavy as his fingers slowly traced his bottom lip, remembering exactly how Senku tasted, the sensation of his legs closing around his head as he begged - not with his words yet, only with his body - but it was worth it, entirely. Xeno's fingers slowly traveled down his torso then, undoing every button with extra care, loosening his tie, stripping himself in a way that felt all too erotic to be doing it alone. He wanted, so much, to pin Senku down after the younger boy experienced his orgasm. He had been stretched enough by then, body able to take his cock, he was sure of it...

But no... it was too soon. He needed to wait. To build up to it. Make sure that when he could finally,  _ finally _ , be completely one with him... that Senku would be clinging and moaning out as he begged to be fuck harder. Yes... waiting until then would be the best. 

It did not make Xeno's own predicament any easier, though, cock painfully hard within his pants. He was quick to undo them, sliding them as well as the rest of his clothing from his body. With a hand braced against the sink, Xeno slowly started to wrap his palm around the needy erection, a moan catching in his throat -- but he stopped. Usually, Xeno did his best to hold in such noises, never wanting to alert nosy neighbors to what he might be doing. But Senku was close. It could do the boy some good, hearing what he had caused. So Xeno let out a low, breathy moan as his grip tightened, his pace slow enough to only be a tease. He did, in fact, intend to take a shower. He just needed something, even if it was just a small touch. 

The shower soon turned on. It would muffle his noises, but not by much. He needed to be humble about it... not too much noise to make it seem as if he was acting. Just loud enough that Senku could make them out. The hot water felt great on Xeno's skin, but not as great as his hand finally starting to pump away at his cock, greatly aided by the water running down his body, a series of small moans escaping from his throat.

Senku pulled his underwear back up, face still flushed bright red as he laid still on the mattress. He wanted to get up and set up the couch for him to sleep on, but his limbs felt like jelly when he made a move to sit up. There was nothing wrong with laying there for a few minutes, was there?

At least, that's what he thought before he started to hear some odd noises from the bathroom. Hushed groans, muffled by the running water. Senku shouldn’t have been surprised, of course Xeno was going to get off to that, but there was something so different when he actually heard it.

Something stirred in his stomach as he listened, a slight heat in his core that was now all too familiar. No, no,  _ nonono _ . He shakily got up, he did not want to listen to this, and he certainly didn’t want his traitorous body feeling anything in response to it. He distracted himself by grabbing an extra pillow, and blankets, which he brought out to the couch. Maybe he would order food, Xeno had said he could use his card…

Senku spent probably too much time making his “bed”, assuring that it was clean and comfortable. He’d set his stack of books on the side table, along with a glass of water. He realized that he didn’t actually know any of the restaurants nearby, so he had resorted to making dinner for himself. Eggs and toast weren’t exactly the best thing to eat before bed, but he had missed the window for a proper dinner anyway.

In the bathroom, Xeno's breaths finally evened out, leaning his body against the shower wall, a held out hand being washed by the running water. His orgasm was great, imagining Senku panting and crying beneath him, but it was far from amazing. Oh well - he would get to taste that sweet fruit again soon. He had an actual task now - cleaning his hair and body. He still had work in the morning, and a lot of planning to do for the future, if he was going to be taking the time off. 

Once out of the shower, a simple towel around his waist, Xeno returned to his bedroom to see that Senku did not clean up at all. Though, Xeno did not expect this in the first place. Xeno dressed himself first, simple soft pants and a plain shirt, which was the closest Xeno got to casual clothing. Once covered, he set his mind on cleaning up his bed, the speculum still wet with recent lube. A smile pulled at his lips just looking at it - but all such items went away into the box from before, alongside all the other experimental items that Xeno would use later on. 

Xeno walked out into the main room of the apartment then, passing by Senku to make his way to the kitchen. Such a long day - Xeno did not find himself too hungry, but a simple drink before bed sounded nice. After pouring some ginger ale into a clear glass, Xeno then made his way back to the living room, sitting himself into one of the arm chairs as his eyes fell to Senku, who seemed to be doing all he could to ignore Xeno's presence. 

"What is it that you do, during your evenings?" Xeno asked then, glancing to the nearby television, "movies? shows? You never have told me what your hobbies outside of work and school were."

Senku had just been sitting down on the couch to eat when Xeno came out, and he did his best to keep his attention on the book in his hand. Of course he couldn’t ignore when he was asked a question, and he finished the bite he was taking. “I would usually play a game, but my console isn’t here yet…”

Xeno's grin grew, sipping at his drink, "poor thing, you'll be so bored." Senku was giving off that aura of not wanting to talk. Understandable, seeing as it was probably pretty hard to hold a casual conversation with the man that was just tongue deep in your newly acquired sex. With a content sigh, Xeno stood, grabbing the remote for the television from the coffee table and placing it on the side table near the couch. "Feel free to watch whatever you want - there are a few different streaming choices available." 

Xeno turned from the living room then, taking the steps to head towards his bedroom, but he stopped before he could get too far. "Oh, right. I had almost forgotten." His attention then turned back to the kitchen, finishing off the drink before placing the glass into the sink. His wallet laid out on the counter top, and it only took a moment of digging inside to pull out the exact card he wanted. He then walked to Senku, standing right in front of the boy, reaching down to take his hand. Turning his hand up right, Xeno placed the NASA issued credit card into his palm, forcing Senku's small fingers to curl around it. Before letting go, Xeno leaned in close, lips nearly grazing Senku's ear, voice purring as he spoke, "for your services." 

He let go then, lips curled into a mischievous smile before turning once again and heading to his bedroom.

Senku stared down at the card in his hand, his face red at Xeno’s proximity and whispered statement. “D-don’t say that! It makes me sound like a prostitute or something!” He pouted after Xeno as he left, before placing the card on the side table. Maybe he could buy himself a new game later on with it.

He sighed softly, laying down on his makeshift bed and turning on the TV. He doubted he could get any of the shows he normally watched at home, but there was no harm in looking… and he found himself pleased to find a few seasons of the most recent Doraemon series. He turned the audio down and enabled captions, it was easier to read than to listen, and he didn’t want any ridicule for watching such a childish show. It didn’t take long for him to fall asleep though, his eyes fluttering shut and blocking out the sight of his favorite childhood character while he drifted off.


	5. Experiment 05

Sleep came rather easy, seeing as the day had been full of a lot of events, and the fact that Xeno's previous night had only been a small nap atop his computer desk. There was no time to daydream about his assistant or the tools in the box or the things he wanted to buy for the future - as soon as Xeno's head hit that pillow, he was out for the night. 

If he dreamed, he did not remember, eyes soon opening and adjusting to the sunlight entering the room from the nearby window. He stood with a yawn and a stretch, checking in the mirror only for a moment to fix any bed head. He was not bothering much with keeping things perfectly slicked back, not at least until he had his morning coffee, but there was no need to walk around the house with a bird's nest on his head. 

Xeno kept his footsteps quiet as he exited his room, walking past the couch in the living room and making his way towards the kitchen. Though - something stopped him, looking at the television. It was still on, though the playback of the show had stopped, a screen now asking  _ 'are you still watching?' _ Behind that, however, was a strange blue cartoon creature. Xeno looked over the couch, making sure Senku was asleep, and sure enough saw him sleeping peacefully. With careful movements, Xeno grabbed the television remote, making sure the volume was muted before he clicked the 'yes' button. 

The cartoon continued to play. The title read 'Doraemon', something completely lost to Xeno. The animation was easy to place, though, an older Japanese cartoon. Did it happen to turn on, just part of a randomized queue...? Or...

Slipping into the 'episodes' tab, it was easy to see that not only this episode had been watched, but a huge handful before it. Senku had deliberately turned this on. A small smile pulled at Xeno's lips - now remembering those images of Senku at some sort of museum, the blue cat creature in the background. So, Senku had a nostalgic love for some childish cartoon. _ Cute.  _

Xeno placed the remote back down, returning to his task of making some morning coffee. He had a few tasks that morning before work. But the blue cat cartoon put a new idea into Xeno's mind. Such an old show had to have merchandise, right...? 

As Xeno sat at the computer in his office, coffee freshly made at his side, he learned that this character had... a lot more than just merchandise. In a way, he seemed to be like Japan's version of Mickey Mouse. Old merchandise, vintage, new things. Dinner plates and bento boxes, clothing, backpacks. And, a lot of it... was targeted towards children. 

_ Perfect. _

Xeno sipped at his coffee, a smile on his lips as he finalized a new purchase. The items would be coming from overseas. They would take awhile. But they would be worth it.

Senku woke up late again, rubbing the sleep from his eyes and smoothing down his unruly hair. Xeno wasn’t there, probably in his office, so Senku made his way to the kitchen. The coffee pot was already full, and he poured himself a cup. He likely should have been suspicious of it, but he really didn’t have much to lose anymore. 

He leaned on the counter and munched on an apple, racking his brain for things to do. His roommate would drop off his things later, he could just explain he was staying with his supervisor to save on travel time, and he could tell the front desk that he was Xeno’s nephew or something.

After double checking that the bedroom and bathroom were empty, Senku found an outfit, and went into the bathroom to change. It was simple, a plain t shirt, a pullover hoodie, and a pair of shorts that reached almost to his knees.

When he came back, he quickly turned the TV from Doraemon to some documentary. Xeno had probably seen what he had been watching anyway, but maybe he could brush it off as sleeping on the remote, or wanting something familiar to fall asleep to.

With his purchases complete Xeno left his office, making sure to lock the door behind him. He could see now that Senku was awake, but paid him no mind at all, sipping at his coffee as he made his way to his bedroom. He wasted too much time on the computer, he would have to be off quicker than usual. He dressed in his usual work attire, slacks and a dress shirt, a tie, and the two collars around his neck. People always questioned them - he enjoyed their raised eyebrows as he never answered them. 

Exiting his bedroom, Xeno walked to the main entryway of the apartment, wrapping his coat around his body. "I will be back from work around five tonight. You are welcome to do as you wish. Please pick up after yourself." There was a part of Xeno that wanted to tease the boy - lean over the couch and ask for a kiss goodbye. But he saved such thoughts. Acting as normal as possible would be best, for now. So he walked out the door with no other words, closing the door behind him. 

Many things needed to be done that day. Discussing with work about his new from-home schedule. Calling in for Senku himself, both to his school and his internship, as he promised he would do. It would be simple - though he planned to encourage Senku to take on a few online classes. If he did not have a laptop, Xeno could provide one.

Senku rolled his eyes at the order, and leaned back on the couch. He was sure he would be bored today, not like he could make much of a mess with what he had available to him anyway, so he resigned to just watching TV until he got confirmation from his roommate that he had dropped off his things.

Senku passed his time mostly with the television, flipping from documentaries to dramas to cartoons as the day wore on. In the early afternoon he got a text from his roommate and headed downstairs to meet whoever was manning the front desk. He introduced himself as Dr. Xeno’s nephew, and the backpack of items that was just dropped off was his. After correctly saying what was in the bag, the attendant handed it to him, and he made his way back up to the apartment.

Everything he had asked for was in there. His laptop, his Switch, some textbooks, energy drinks and packs of ramen he had left in the dorm… he set a pot of water on the stove and hooked his Switch up to the TV, before finally settling in to play some games until Xeno got home.

* * *

Everyone at work seemed weary for the boy. Many asked Xeno why Senku had not come in to work, such an oddity for the young man, but Xeno simply explained that he was focusing on his school work and would continue to still assist Xeno through other means. It took a few lengthy emails to some of their higher bosses to allow Senku to keep his internship, but as long as Xeno was signing release forms to confirm that  _ yes _ , he was in fact still aiding, he would be allowed to not come into work directly. 

As for schooling - a lot of that would have to be up to Senku himself, Xeno only having so much clearance with such things. But contact did happen, to ensure the school that his internship was still valid, and that the boy would be looking into online courses for a while as he focused on family life. It helped a bit that Xeno's name was well known at the school, the nearby college having quite a lot of courses focused on the study of space and physics. 

Xeno then focused on getting things ready to work at home. It was a simple feat, seeing as most of his work happened through the computer in the first place. Most changes happened with his schedule - though Xeno would still be coming into work every Monday and Wednesday for lab work that simply could not be done in a city apartment. Once everything was out of the way, Xeno focused on his work, finding himself missing the inquisitive voice that would always sound off next to him. 

It was no worry, though. That voice would be waiting for him at home, now more higher-pitched than ever. 

* * *

The weekend had finally come. 

Xeno had spent the past few days acting... rather  _ domestic _ . He did not ask Senku for any more experiments, instead letting the boy focus on getting his schooling figured out - a task that Senku constantly had to remind Xeno would not be an issue at all if he didn't think slipping stuff into people's drinks was such a splendid idea. But, for the most part, Xeno kept his hands entirely to himself. Aside from the occasional grip on the boy's shoulder as Xeno would lean over him from time to time, or the tug at Senku's shirt to tell him that he definitely needed better fitting clothing. 

But - that would change. That morning, Xeno sat at the table near the kitchen, enjoying his usual morning cup of coffee as his laptop showed snippets of the morning news. He could hear Senku awaking, waiting for a moment before calling out to the boy, "you should take a shower and get ready. We are going out, today."

Senku let out a groan and a yawn as he sat up, nodding at Xeno’s suggestion. “Alright… where are we going?” He rubbed at his eyes before standing up and making his way to the kitchen for his usual cup of coffee. He had finally gotten a grip on his online classes, though of course he wasn’t too pleased about it in the first place. He much preferred being in person, seeing everything firsthand, rather than making a discussion post and replying to two classmates. At least he had managed to avoid video or voice calls thus far, citing poor internet connection and an old laptop.

No matter where he and Xeno were going, this was going to be his first time leaving the apartment building in nearly a week, so it would make sense for him to be eager. Once he had finished his drink, he stopped in the bedroom to grab an outfit before rushing off to take a shower, and emerging just a little while later. "Ready?"

The idea of going out seemed to excite Senku, the boy quickly going through his morning routine. Xeno could have been taking him absolutely anywhere at that point and Senku would have happily agreed. But Xeno's plans were actually rather... open. 

He got fully ready himself as Senku was in the shower, giving the boy a warm smile once he walked out, fully ready. He gave a nod, grabbing his coat and car keys from the nearby table, heading out into the hallways of the apartments. 

"I actually do not have a concrete plan for the day," Xeno said as they entered the main elevator, pressing the button to send them both down to the garage. "The main goal for the day is to find you some better fitting clothes, as well as some real shoes, seeing as I had no idea what size you could be. But where we go, that's up to you. I am sure you have some places you would like to visit, seeing as you'll be cooped up more than usual." 

The elevator brought them straight to the garage floor. For a split second, Xeno thought about the couples that would share intimate moments on elevators... but such a thing would be idiotic. Cameras were installed into these things, and Senku looked like a child now. 

As they walked through the garage, Xeno continued, "I really don't mind where you wish to go - though, I'd rather not drive to the entire other side of California. If you could stay in the San Francisco area, that would be preferable." 

Once situated in the car, Xeno started the engine, giving a smile to the boy in the passenger seat. The last time he sat there he was not only much bigger, but only half conscious and terribly confused on what was going on. But it was best to not bring such things up. "Well? Where would you like to go?"

Senku settled down in the car, buckling himself in before leaning back against the seat. “It might be stereotypical to say Japantown, but the shops there tend to carry smaller sizes, so I can still look a little more professional than the clothes in the children’s section.” Of course, he might browse the kids’ section a little bit. There was no reason he couldn’t have a few things pertaining to his more childish interests. 

He stared out the window for the rest of the ride, listening idly to the music that was drifting through the speakers. He wouldn’t have guessed Dr. Xeno to be a classical music fan, but it fit well with his affinity for elegance. He closed his eyes for a little while, coming up with a mental checklist of things he might want or need. Clothes were the main goal, but Xeno probably wouldn’t have an issue if Senku wanted to get some books, some nostalgic snacks… if he was going to look like he was 14 again, there was no reason he couldn’t indulge in some of his favorite things from that time, right?

The silence of the car ride was actually quite nice, and Xeno found himself drifting off into thought occasionally. His gaze would often float over to his companion in the passenger seat, a smile curling a bit every time that he did. Xeno knew that Senku's mind was still that of an adult. That may have been the reason that he allowed himself to truly indulge in the most degenerate of thoughts. But right now, out in public, Senku's small frame in the seat of his car, pale knees showing off beneath his shorts... he really did look like a young teenager. 

He would have to claim to be his uncle. Through marriage. They looked nothing alike. 

Xeno knew where Japantown was - but that did not mean he knew anything about the place. Eventually, parking was found, not too far off from the shops and restaurants themselves. Senku helped to direct Xeno through the city and to the main Japantown shopping center, then hopped out once they parked. Upon getting out of the car, Xeno removed his coat to leave it behind, noting that the sun was high and the weather seemed just fine enough to not bother with extra layers. Once Senku came around to the other side of the car, Xeno shot a smile his way. "I have never been here, so you'll have to lead the way. We can have lunch as well, wherever you wish."

“I know my way around, I figured I’d check when I first got here.” He headed off towards the center, not bothering to make sure that he was being followed. “I know of a couple different clothing stores, so we should check them first.”

He was able to find the store fairly easily, and he left Xeno to his own devices while he browsed. He grabbed a few shirts that looked like they’d fit him, both button up and t-shirts, as well as some jeans and sweatpants, and a pair of sneakers. He’d try these on, and then check the children’s section if they didn’t fit. Once he had everything he wanted to try on, he went and found his chaperone. “I’m going to see if these fit, I should be ready in a few minutes though.”

Xeno gave Senku a warm smile as he nodded, though the way Senku turned immediately towards the dressing rooms gave Xeno the impression that he needed no help when it came to changing. It was silly - to feel a bit of pride in the young boy being so independent, knowing he was technically an adult. There was technically no reason that Xeno needed to follow. Senku could handle dressing himself. 

But where was the fun in that?

Xeno had eyed something when he first came into the store. Something he would love to see Senku in, but knew the boy would refuse him out right the second he saw it. But there was a plan hatching in Xeno's mind. An idea made even more perfect as he made his way to the dressing rooms and saw no one around. No one to check item numbers with, no one to watch over the stalls. Perhaps the women's side of the store had more activity. But not here. They were almost perfectly alone. 

Only one stall was preoccupied, which (hopefully) had meant it was Senku. With a gentle knock, Xeno called out to his assistant, "Senku? Humor me - I think I found something you would like. Open the door."

Senku had finished putting on the first couple articles of clothing, a short sleeved button-up and some skinny jeans, when the knock and Xeno’s voice reached his ears. He let out a quiet sigh before peeking out and glowering at Xeno. “What is it?”

That was all Xeno needed - that small opening of the door. It was a risky gambit. Senku could freak out, call him out, or even try to call for help. But he had hoped Senku would be smart about this - Xeno was his only ride home, and the only one who knew what was going on with his body... So Xeno let his hand slide into the room, grabbing at the door edge and easily pulling it open, his strength still greater than the boy inside. Before Senku could object, Xeno made his way inside, closing the door behind him, acting as if nothing at all was odd with his intrusion. 

He sat then, on the dressing room bench, holding up the exact thing he had picked out. Frilly. A beautiful pastel blue. A tight fit at the top before flowing out into a slight bell shape. It was a dress, just about Senku's size, covered in a dusting of metallic stars. "I think this suits you quite nicely, don't you think? At least - I thought of you when I saw it."

Senku squeaked in surprise as Xeno entered the dressing room, making an attempt to push him back out, but of course failing miserably. He wasn’t very strong to begin with, but he was even weaker when he was a teenager. He supposed it didn’t matter too much, he was fully dressed… at least until he saw what exactly Xeno was holding.

“No. No. Absolutely not.” Senku shook his head, and quickly opened the door and made an attempt to push Xeno out. “Go put it back now.” His face was bright red, the intent behind the dress was obvious, and he did not want to even entertain the idea.

Xeno's expression did not change one bit as he stood, placing his hand over Senku's and forcing the door shut. He stood towering over the young boy, small hints of a smirk curling at the corner of his lips. "You seem to forget that the one spending so much money on you today... is  _ me _ ." His hand lifted from the door, holding up the flowing blue dress against Senku's body. Yes - it seemed to be the perfect size, or at least close enough. 

Xeno gripped at Senku's shoulder then, forcing the boy to turn around and face the changing room mirror. He held the dress against Senku's body once more, looking to the mirror himself, noting how it would hit just above his knees. "It'll look amazing on you," he said, though knew that no matter of flattery would convince the boy to actually try it on. So, instead, Xeno leaned low, lips barely grazing at Senku's ear as he spoke low, "how about a deal, then? Wear this for me, and I will leave. A simple request, don't you think?"

Senku stared at himself in the mirror, the bright pink shade never leaving his cheeks. He briefly met Xeno’s eyes in the reflection, before letting out a sigh of resignation. “Fine. But we’re not buying it.” He took the hanger from Xeno’s hands and stepped away from him, eyes narrowed. “Now get out so I can change.”

One battle won - the next part would not be as easy, but Xeno's reserved smile stayed as he sat back on the changing room bench, his hands folding on his lap. "I believe you misunderstood me, Senku," he began, taking a moment to look down at the dress before locking eyes with him once more, his eyes creasing as he smiled wider, "I do not intend to leave." He raised his hands then, as if offering a surrender, "I will not attempt to touch you as you change. I promise you."

Senku could feel the warmth in his face quickly spread to his ears and down his neck. He shouldn’t feel so embarrassed, Xeno had his face between his thighs less than 24 hours ago, surely getting changed couldn’t be that much different, but… at least the day prior, he could messily explain it away by saying they were just trying to see how arousal impacted his new genitalia, but this didn’t have an excuse. This was pure perversion.

But there wasn’t much Senku could do about it, was there?

His lower lip quivered in a semi-purposeful sign of embarrassment, and he hung up the dress on one of the hooks before unbuttoning his shirt, and folding it back up, before hesitantly removing his pants as well.

Xeno was doing his absolute best to keep his face, for the most part, entirely blank. Though, his smile was an obvious sign at how much he was enjoying himself. But, if Xeno was not careful he was sure that his true side would come out, his dark stare threatening to show on his face, the absolute delight to see his assistant give such a defeated and pathetic face. His stare did not falter one bit, not a bit of shame in his mind as his eyes wandered down Senku's body, lips curling once more as he saw the star and rocket decorated underwear. Of course he wore them. They were all he had. But, Xeno had promised not to touch. His hands slowly folded together, focusing on his breathing instead of the growing warmth in his groin. Senku didn't even know it, but he was giving a beautiful show.

Senku didn’t know why he was shaking so much when he took the dress off its hanger, a mixture of shame and the chill of the air conditioner, probably. The dress was made up of two parts, an opaque, form fitting inner slip, and a bodice and skirt made of sheer blue chiffon, adorned in frills and silver stars. He undid the tie on the back of the neck and stepped into the dress, pulling it up and adjusting the fit before reaching back around to re-tie the ribbon.

The inner dress was obviously meant for someone that had less of a boyish figure. It was loose around the hips, and the built in cups sat stiff and empty against Senku’s chest, though to the naked eye they gave the illusion of small breasts, much to his frustration.

“There. Happy now?” He crossed his arms, hoping his expression came off as a glower, but his rounded cheeks turned it into a pout.

It was stunning...  _ perfect _ . If Xeno wasn't as smart as he was, he would have brought out his phone to get a few pictures. But instead, he stood, getting a better look at Senku through the mirror. Senku looked absolutely uncomfortable, nothing about his posture seemed to suggest that the boy felt any semblance of confidence in the dress. But that, somehow, only made it better, watching the way his lip softly quivered, or how his shoulders stayed so tense. 

Xeno upheld his end of the deal - no touching while he was dressing. But the boy was all dressed up, now. Which allowed Xeno to slowly move his hands beneath Senku's arms, palms against his torso and chest as he cupped at the non-existent breasts. "You look fantastic," Xeno let out, his voice low. He needed to be careful, no telling when someone may come by. His face moved down, cheek against Senku's as he looked into the mirror, eyes traveling down Senku's body. "If we cannot buy this, then there is reason to have fun with it now, don't you think? It would be such a waste," his hands then traveled slowly down Senku's torso and hips, eventually grabbing low at the dress. However, before even daring to tug upwards, Xeno nuzzled into Senku's temple, his voice a low and husky purr, "I would advise you to not make a lot of noise."

Senku stared at himself in the mirror as Xeno doted on him, tensing at the touch from deceptively gentle hands. He was sure if a girl had been wearing the dress he would’ve thought she looked nice, but wearing it himself made him feel so dirty, especially with the way Xeno was touching him over it. 

His heart sped up when the hands on his chest traveled lower, and he took a sharp breath when Xeno finally took hold of the soft fabric of the skirt. He silently thought over his options, or lack thereof. Sure, he could physically break away, run to the other side of the store, and bawl to the store attendants about how his ‘uncle’ was touching him. But that would leave him alone in this body, the one he was ashamed to tell anyone about, the one he couldn’t fix if he tried. His only means of returning to a relatively normal life was right behind him, ready to violate him as soon as he was given acknowledgement. He finally closed his eyes and pursed his lips before giving a slight nod.

The nod - Xeno wasn't expecting  _ that _ . As Senku's eyes had closed, Xeno figured that Senku had finally realized that there was no point in really fighting it. But the  _ nod _ . That little nod unlocked a dozen new possibilities in Xeno's mind. His grip on the dress turned hard, doing his best to keep his usual calm and elegant composure. Slowly, he lifted the dress, but it only showed the slim slip beneath. 

That was easy to fix, of course, Xeno's hands now caressing once again at Senku's torso, now beneath the sheer outer fabric of the dress, hooking his fingers beneath the hem of the underdress before tugging the slip upwards. It did not take long until the cute underwear had been revealed, Senku's thighs seeming to be trembling beneath them. "Now, now," Xeno whispered out, his voice honeyed and sweet, the palm of his hand now rubbing against the soft skin, as if his touch would actually calm Senku's nerves. "We've already done so much more than this, there is no need to be so nervous." 

In a quick motion, Xeno sat back onto the dressing room bench, pulling at Senku's torso and forcing him to sit onto his lap. "Ah - you know, I just thought of something," Xeno's voice was still a whisper, but there was an air of excitement to it as he grabbed at Senku's knees, making the boy open his legs wide. "I don't think you've gotten a real good look at yourself yet, have you?" One of Xeno's hands held tight on to Senku's torso, keeping him secure as the other sank between his legs, a single finger tracing at the slit of his sex. It was so cute with the childish underwear - but a simple tug to the underwear let them bunch at the side, allowing Xeno's fingers to form a 'V', spreading Senku wide in front of the mirror.

Senku kept his eyes firmly shut the whole time, his fists held in a white-knuckled clench at his sides. “Th-this is  _ different _ , and you know it…” He mumbled, before letting out a squeak at the sudden movement. He still kept his eyes closed, his fists shaking, but allowed for Xeno to spread his thighs, as much as he wanted to close them. He let out a soft whimper at the sudden cold against his sex, and he shook his head. “I… I don’t want to see.”

"Oh? You're missing out..." Xeno's fingers slowly traced along Senku's slit, never fully touching his hole or his clit, only teasing the skin around his most sensitive parts. Xeno was now able to bury his nose into the crook of Senku's neck, letting his lips graze the soft skin, occasionally looking at the mirror to get a good peak at the view. Even if Xeno could not take a real picture... it would be a sight he would remember. Such pretty pink skin, just now starting to glisten. Xeno's fingers sank down, sliding against Senku's hole, fingers soon wet and spreading it further up and across his clit. 

Senku’s lip quivered as he tried to resist making small noises. He didn’t want this, right? He was just reacting naturally to these touches, it was fine. He could still retain his dignity, at least for now…

"You act so against this... but your body is already waking up. Do you enjoy it, Senku? Knowing that I am looking at your body?"

Senku did let out a tiny, embarrassing squeak when Xeno’s fingers finally delved into his sex, and he tensed up. “N-no, I… I don’t… i-it’s just a natural reaction.” He shook his head. “It’s your fault…”

The shaking of Senku's head was just too damn adorable. Xeno couldn't help himself, beginning now to leave small chaste kisses to Senku's jawline. Two of his fingers slid across Senku's clit, pinching and rubbing the sensitive nub between them. Every little pinch or even a pull was causing Senku's knees to involuntary jerk and shiver, a sight that was becoming a little bit.... too much to watch. 

Xeno had held himself back so many times. Through every single moment touching Senku, Xeno made sure every bit of his attention was on the boy. He could take care of himself afterwards, giving Senku chances to rest. It would be stupid of him to try and take the boy's virginity here in public. No - he needed to do that in a place where he could really hear Senku's voice scream out. But that did not mean he could not join in the fun in a less invasive way. 

Xeno leaned back, tugging Senku's body to sit a bit higher on his own. It allowed Xeno to pay a quick pet of attention to his own clothing, a small bit of careful maneuvering needed to release himself - a shuddering breath leaving him as he felt that sense of relief of no longer being so constricted. Xeno could see from the mirror that Senku's eyes were still closed, but it didn't matter much, hand grasping at his cock and pressing it up against Senku's heat, biting his lip as he refused to make any sort of noise, but a chill running through his body at the sensation of Senku's sex pressing against him.

Senku kept his lips firmly pressed together for the assault on his clit, each pinch and pull making him want to whimper or cry or moan, but he couldn’t allow that. He couldn’t make any noise lest they get caught, and he couldn’t give Xeno that satisfaction.

The only noise he made was a quiet sigh when Xeno’s fingers left his heat. He didn’t pay much notice to the repositioning, and he tried to ignore the sounds of unzipping and fabric rustling… his eyes only shot open when he felt hardness press against his sex. “No. Nononono.” He whispered, trying to wiggle away without accidentally grinding against Xeno, but likely failing.

"Shhh, shh," Xeno softly purred into Senku's ear, petting at his stomach, "There's no need to worry. I don't intend... on  _ taking  _ you here". Even still, the tip of Xeno's cock traced the sweet opening of Senku's sex, before running up along his clit, spreading his juices across both of them. "In fact... there's something easier..." 

Xeno tugged at Senku's legs, forcing his knees together, clasping his thighs around Xeno's cock. "Keep them nice and tight, now... It'll feel good for you, too." With a careful rock to his hips, Xeno was able to pull back, his cock disappearing between Senku's folds, before thrusting forward once more. A shaky breath left his mouth, lips once again leaving small kisses down Senku's neck, continuing the movement once more. He could feel Senku's wet sex against him, slick and hot, but he needed to keep quiet, keep in control. Losing his composure would be most inelegant. 

Senku whimpered softly, his thighs witching each time the skin of Xeno’s cock rubbed against his clit. He was breathing heavily in an attempt to not let out any noise, and as much as he wanted to spread his legs wide again, he didn’t want that to be an invitation to take him fully. He wanted to retort against the borderline condescending words, but his mouth felt dry, and he didn’t trust himself not to let out a pleased noise.

His gaze fell to the mirror, his hips continuing to rock into Senku's tight thighs. It was so easy to see Senku's furrowed brow and thin lips, doing his absolute best to not make a single sound. "Do you still not wish to look?" Xeno said, a hand coming up to run into Senku's hair, grasping at the roots to turn his head to look towards it. "I think you should - maybe then you'd realize why I can't seem to keep my hands off of you..."

Senku nodded at Xeno’s question, making an attempt at keeping his eyes squeezed shut and his face down, only to be jerked back, his eyes opening in surprise. Once he caught a glance of himself, he couldn’t seem to look away.

He looked pathetic. The dress bunched up around his waist, his face red, the way his arms and legs quivered, more and more fluids being spread each time the head of Xeno’s cock bucked up between his thighs… he let out a silent sob, quickly losing sight of the mirror as his eyes blurred with tears.

The sight of the tears - immediately Xeno could feel his peak rising from that alone. His grip in Senku's hair made it easy to keep him still, kissing away every single tear that started to slide down his cheek, "there's no need to cry... you look stunning." Another sharp thrust, Xeno's hips grinding into Senku's thighs, already wanting so much more, "beautiful, even. Oh, how I would love... to see you in all kinds of dresses." Soft moans were escaping from Xeno's lips, breath getting heavier as his muscles began to tighten, his peak nearing. He needed to stay quiet, something usually so easy but it was starting to feel impossible as Senku shivered and sobbed on top of him.

Xeno's grip in Senku's hair began to tighten, lips pressed hard against Senku's temple, breathing in deep as he thrust high one last time. His hips shuddered as strings of cum quickly began to cover the blue dress, with later shots not making it as far, covering Senku's sex and thighs. A low and shaky breath escaped Xeno's mouth - he had held his breath, it was the only way to not make any alerting noises. He stayed there, his grip still tight on the boy until his mind finally began to collect itself again. The sight in the mirror was even more beautiful than before, Xeno's eyes watching the reflection of his hand as he moved down, sliding a finger between Senku's folds, rubbing the mix of Senku's fluids and his own cum against his clit. "Be honest - have you come yet? Do you need me to fix that for you?"

Senku had let out another whimper as Xeno neared his release, wanting so badly to cry out from the pain of his tight hold, but not allowing himself to. He couldn’t be seen like this, he couldn’t… he let his head hang when Xeno finally let go, a shiver running up his spine at the touches. “N-no… I don’t… I don’t want to.” He groped around for something to wipe himself off with, disappointed that there was nothing besides the clothes he had to put back on, and items he still had to purchase.

Xeno hummed softly, giving a few more slow and teasing rubs to Senku's clit before letting him go entirely. If the boy didn't want to ask for it, then he could go throughout the rest of the day with wet underwear and the pent up sexual need. "Have it your way, then," he said, standing from the bench, lifting Senku for a moment before putting him onto his feet. He tucked himself away then, fixing his clothes to look perfect, before looking down to Senku's dress. 

"Ah," he leaned down, running a finger near the bits of fabric that were covered in new stains. "It would be wrong to put it back on the shelf. Looks like we'll be buying it after all." A sinister smirk grew on Xeno's face, eyes locking to Senku's, "I'll let you finish changing, then." 

Xeno opened the door, looking outside first to be fully sure no one was around before stepping out, closing it behind him. "I'll be waiting near the cashier. Let me know when you are done shopping." Xeno didn't wait for Senku's reply, checking one last time that his clothes were nice and tidy before walking away from the dressing rooms.

Senku stared at himself in the mirror, eyes red and puffy, tear-stained cheeks, clothes rumpled and dirty… he was a mess. A pathetic mess. 

He tried to ignore the new tears that sprung up as he removed the dress, quickly wiping away any excess fluids with the inside of the inner slip, before folding it in a way that hid the new white smears. He didn’t bother trying on the remaining clothes, the first outfit he had tried on fit well enough and they were all the same size. He quickly wiped his face clean with his palm, taking a few deep breaths to calm himself, then headed back out into the store.

Senku wandered around the store for a little while, grabbing some plain underwear and socks, before ducking into the children’s section just to see if anything caught his eye… two sets of pajamas, one doraemon and one space themed, made their way into his arms as well, before making his way to the checkout. He headed up to the register with Xeno, and placed the pile of clothes on the counter.

Xeno could see that Senku was doing his best to not look upset. His eyes avoided looking directly at Xeno as he put the clothes on to the counter, nor did he pay any attention to Xeno as the cashier slowly rang up the clothing. Though - Xeno did notice the quick look of panic on Senku's face as the woman held the blue dress. Luckily, the woman did not unfold or inspect it, simply ringing it up and placing into the bags with the rest. 

Xeno paid for the total - not as much as he expected but still quite a lot more than the department store - holding most of the bags as he walked out of the store, Senku following slowly behind. He looked to the boy with his usual reserved smile, "do you know what store you want to go to next? Also - it's nearly mid-day, any idea on where you'd like to eat?"

Senku held one of the bags tightly in his hand, staring at the ground as he walked. “Um… there’s a bookstore I want to go to, and there’s a ramen place next to it…” His voice was much more timid than before he had gone into the dressing room, and a bit shaky. He was sure Xeno noticed, but he didn’t care.

Once they got to the bookstore, Senku wandered around the various sections, pulling down a couple books that seemed interesting. He also grabbed a journal, and a large Nanoblocks set, all of which he took to Xeno for approval.

The bookstore, unlike the clothing store, was one that Xeno finally found himself getting lost in as well. While a wide range of titles were in Japanese, there also seemed to be a wide range of English as well. Once Xeno had a few books under his own arms, he turned to find Senku holding the handful of items. Was he looking for permission?

With a soft chuckle, Xeno reached down to run through Senku's hair, ruffling it gently, "I told you, didn't I? This trip out is for you, you can have absolutely anything you want." Xeno took the items from Senku, looking over the few books as well as the lego-like toy. If they were anything like legos, then the set would be far from cheap, but that didn't matter. As he said - this trip was about Senku, after all.

Senku blushed a little when Xeno ruffled his hair, but nodded slightly as he brought the items up to the cashier. The toy was fairly expensive, but… it would keep him occupied for a few hours at least. He volunteered to carry the bag, figuring that Xeno was already carrying enough.

Once out of the store, even more bags in tow, Xeno turned to face Senku once more, "we could stop for lunch. Afterwards, you're welcome to wander around more. I doubt there are only two stores you wish to go to, after all."

“Th-that sounds good… maybe we should go back to the car first, so we don’t have to carry everything around?” He wasn’t very strong as it was, but especially not when he was shaking so badly after his… experience with Xeno earlier.

Xeno gave a nod, "actually, that's a great idea," he held up the many bags of clothing - but the books, that definitely bade everything heavier. 

They made their way back to the car, dropping off the many bags into the trunk before setting right back out. Senku was thankful to be rid of the weight from his arms, and quickly grabbed his sweater before they made their way out of the parking garage.

Senku knew exactly where to go for the ramen shop, considering he had gone there a couple times after a classmate had told him about it. It was good, obviously not as good as his favorite restaurant at home, but it made a decent substitute. The crowd had gotten a little bigger while they were in the parking garage, and as much as he didn’t want to, Senku took Xeno’s hand to keep either of them from getting swept up.

As soon as they were out of the thick of the crowd, Senku immediately dropped his hand, and followed the hostess to their booth. Normally he was able to sit just fine, but now with his shorter limbs, he could just barely touch the ground with his toes, making him feel even more like a child. Why couldn’t he have only gone back to 16, after his growth spurt..

Xeno hummed softly as he looked through the menu, eyes dancing around terms he actually, for once, was not super familiar with. It was not often that he frequented Asian themed restaurants, and especially not one that tried to remain more authentic. "I assume," Xeno spoke softly, looking at Senku over the top of the menu, "you must already know what you want?"

.Senku absently glanced over the menu, already knowing which soup he wanted, but there was no harm in looking over the appetizers and drinks. “Mhm. The Kagoshima ramen. I don't know what to recommend, since I don't know your tastes.”

Xeno glanced down at the menu once more, running his fingers along the names until he fell upon the Kagoshima ramen. "If I am honest with you, I do not have much experience with this pallet, so I may just have to trust your own," he placed the menu down then, "we can have two orders of the ramen, though please, feel free to order some appetizers as well." It must have been obvious to Senku at that point - the blatant spoiling of this entire trip. Xeno was never the type to buy lavish and unnecessary things, so he was happy the money could go to something. A chuckle came to him, thinking over the fact that he was essentially turning himself into a 'sugar daddy'. The only thing lacking was Senku's enthusiasm. 

Senku nodded, he’d probably order some gyoza and edamame, they weren’t too expensive anyway. He knew in the back of his mind that Xeno would insist that he not worry about it, but old habits die hard.

"Senku," Xeno said then, his hands folding and his chin resting atop them, "you have not once looked me in the eye since we left the clothing store. Did our little game back there really upset you that much? Or... are you still feeling pent up from it?"

He stayed silent at Xeno’s observation, and he fiddled with his napkin. “I-it was just… a lot.” He mumbled, still unable to bring himself to lift his gaze. He couldn’t say that under different circumstances it would’ve been as unenjoyable. If he were in his proper body, not in public, in clothes he liked, perhaps with someone besides Xeno… “I’m still not used to all this yet. I mean, it’s only been a week. And… I would’ve appreciated a bit of warning.” He went silent as the waitress returned, thankful for the interruption as he placed his order.

Xeno smiled up at the waitress, speaking his own order which was identical to Senku's. The water and tea was just fine enough for drinks, and soon the waitress gave a small bow before leaving with their order. 

"I would think that _ 'no warning _ ' is part of the fun," Xeno said then, turning back to Senku, leaning his chin into the palm of his hand. "If I pushed past your boundaries, then you have my apologies," Xeno knew full well he had gone far beyond any limits that the boy must have had. But such actions were important if he was to get Senku more comfortable with such acts at a faster pace. "And, as I said..." He had to pause, looking up and tapping his fingers against the table top, being very careful in his choice of wording. "I do not intend to do the  _ full task _ unless it is done at a place and time where both parties can...  _ express _ their enjoyment."

Senku narrowed his eyes at Xeno’s comment, of course he was into that, the creep. “Well… I don’t intend to do the ‘full task’ at all.” He sat back against the vinyl seat, fidgeting with the end of his chopstick wrapper, his glare never leaving Xeno’s gaze in an attempt to assert his dominance. It probably wasn’t working, he likely looked downright adorable to his mentor, but compliance was never really his strong suit.

Xeno arched an eyebrow at Senku's comment. So he was determined to keep his virginity intact? The glare made it even more impactful, Senku had no desire at all to humor Xeno on his wishes. After all - everything before was simply an experiment. But  _ fucking  _ him - or what happened in the dressing room just an hour or so ago, was far from scientific. 

A sigh left Xeno as his eyes closed, though the smile on his lips made him seem far from upset. Senku was strong willed, he knew that. It would take more than a few orgasms to break him entirely. Though, he had hoped it would have been a quicker process... But Xeno was just too soft on him. His need to dote on the boy was getting in the way of his more... carnal desires. 

Though... there was a way. Perhaps. Xeno reached into his pocket, sitting back in the booth as he scrolled through recent messages. Yes. The times worked out perfectly. Xeno would be getting a visitor in just a couple of days... 

Xeno put his phone down, smiling all to himself, looking up as the waitress brought by their appetizers. After giving thanks and watching her walk away, Xeno looked to Senku, "you may do as you wish. After all, acts like that aren't needed for our research," Xeno took a sip from the small tea cup, his eyes never leaving Senku's, "even if every part of you seems to enjoy it."

Senku busied himself with moving a few dumplings onto his plate, trying to ignore the heat in his cheeks. “You can tell yourself that, if it makes you feel better.” He rolled his eyes before taking a bite, doing his best to ignore Xeno’s smile. It wasn’t even confident or cocky, just eerily normal, genuinely pleased. Senku didn’t like it one bit.

He couldn’t make himself break eye contact, as though relinquishing was a sign of weakness. He didn’t want to give in at all, so he had to stand his ground, even on such a tiny thing as holding Xeno’s gaze. Any vulnerability would be exploited, they both knew that all too well.

This was easy, for Xeno. He occasionally sipped the tea, finding Senku's sudden need for a staring contest to be... almost adorable. Was this another way of him asserting his dominance? Did he really think that Xeno was above using a bit of force? 

But the sudden buzzing on the table brought Xeno's attention away - he had gotten a message. If it was from who he thought it was, he'd have to answer soon. With a soft sigh, Xeno closed his eyes slowly, letting Senku win whatever battle he thought he was playing, before looking down to his phone. A familiar name had shown again, only bringing a small smirk to Xeno's lips. It would take a bit of explaining... but Xeno was sure this would work. 

It was not long before their main courses had been brought out. The act of eating allowed both of them to go quiet, no more focus on keeping up the clever banter, though Xeno did compliment Senku on his choice in food, seeing as it was quite delicious. Far from Xeno's usual pallet, but that was the entire point of coming to such a place. Aside from comments on the food, nothing further was said about Xeno's actions in the clothing store, nor Xeno's desire to go even further down that path. 

After lunch, Xeno was brought to more stores, all of them full of exotic and strange things, and more stores meaning more money spent. As upset as Senku wanted to act, it seemed he had no real issue in spending large amounts of Xeno's money. But it was no real problem - Xeno's salary was enough to handle the splurge, and he did tell Senku he could have absolutely anything he wanted. It was not long before the two of them were talking back to the car, hands full of bags, ready to head back home. 

Senku couldn’t say he didn’t like being doted on this much. Even though he knew it was for getting him to let his guard down, he supposed it couldn’t hurt to let Xeno buy him a new game, or some of his favorite foods that one couldn’t get at a regular grocery store. By the time they were headed back to the apartment, Senku was more tired than he wanted to admit, and quickly fell asleep in the car. Thankfully he didn’t wake up while Xeno was carrying him through the building back to the apartment, otherwise his ego would have been badly bruised.

* * *

It was that Sunday night when Xeno finally decided to break the news to Senku. 

Xeno had done well to keep his hands entirely to himself the rest of the weekend - though that did not include the occasional shoulder squeeze, or low whisper into Senku's ear. He enjoyed the flushed glares he would get every time -  _ absolutely addicting. _

But, that following morning, they'd be having a guest. 

Xeno stood in the kitchen, putting away a few dishes. As usual, they had eaten dinner at different times, Senku seeming very intent on staying independent. Senku had finally finished his homework for the night, and settled onto the couch to distract himself with the TV or a video game while Xeno cleaned up. 

"Tomorrow, around noon, a guest will be coming over," Xeno started, looking at Senku who was sitting nearby. "I'll be at work, but he has keys. He knows about you staying here, as well as your... predicament, so you don't need to worry about what you say."

“Sounds good.” He spoke up a little in an attempt to be heard from the kitchen, though he couldn’t help but let his mind wander. Had he met this person before? Did he also work at the research center, or was he unrelated? Why exactly was he visiting when Xeno would be out?

There were no further questions - no asking Xeno who this person was, or how long they would be staying. Then again, Senku had been rather short spoken with Xeno ever since the dressing room. 

That was fine. That would most likely change, by tomorrow night. 

Xeno did not push the subject further, simply finishing his tasks in the kitchen before bidding Senku a good night and heading off to his bedroom.


	6. Experiment 06

The early morning was like any other. Xeno had to work that morning, but starting now he would be working shorter hours, many of them from home. Casually, Xeno spoke with Senku that morning about bringing home a few things from the labs - they needed to continue the work on the serum, after all. 

As Xeno was putting on his coat and double checking his pockets for his car keys, he made a small "Ah-" before turning towards the living room, "my friend will be here around noon. He'll be in town for the week - but don't worry. He'll find... something around the house to keep himself entertained." 

Senku hadn’t bothered to get dressed that morning, staying in his pajamas as he went about fixing his breakfast. “Okay, I’ll stay out of his way, then.” He sat down at the table before opening up his laptop, looking over his coursework for the day. A recorded lecture, a quiz, the usual. He could work on it while the guest was here, then he could move over to the couch when he was done with it.

Xeno opened the door, back turned to Senku so that he could not see the curl of his lips, "don't be  _ too  _ disobedient for him." Without waiting for a reply from Senku, Xeno walked out into the hallway, closing the door behind him.

The morning passed quickly, Senku taking a break from his work to get dressed in a pair of sweatpants and a t- shirt, then to clean up the living room before going back to his homework and working on it until noon. He was only brought out of his focus by the sound of the door opening...

Stanley was staring down at his phone as he walked into the apartment, a large bag held over his shoulder, soon closing the door behind him with his foot. On his phone were a few recent messages from Xeno. The  _ 'rules'  _ of the house, so to speak. Damn guy had a lot of stipulations for this favor of his. But it would be easy enough to follow. 

He walked more into the room, letting the bag drop near the couch - he had been here many times before, but it had definitely been awhile. Nothing had changed much. The same minimalist furniture, a couple 'elegant' decor choices. But one thing was new - and that was the face of the young boy staring at him from the dining room table. At first glance, Stanley couldn't help but give a laugh - the guy really fucking did it... 

Stanley neared the kid (kid? Could he even say that?), scrolling through his phone until he found the page he had searched for earlier, after Xeno had explained the situation. Senku Ishigami - only a small handful of selfies and pictures on his social media page. "He wasn't fucking lying - how the hell did he do it..." He held the phone up, right against Senku's cheek, not giving a damn about personal space as he looked between the much more mature face on the screen, and the one still round with baby fat right in front of him.

Senku almost said hello, before he was interrupted by the man laughing and talking to himself. That coupled with the clear lack of boundaries, this was  _ definitely  _ the friend Xeno had been talking about. 

“Nothing short of a miracle, clearly.” He reached up and pushed the man’s hand away, before turning back to his laptop, immediately getting back to work on surely his fiftieth discussion post of the week. “you feel free to go about your business until Xeno gets home, I won’t bother you.” He had to stop himself from grimacing at the lingering smell of cigarettes, figuring Xeno would want him to be at least a little bit polite.

Stanley began to smile wide, taking a seat right next to Senku at the table, looking the boy over. Xeno would  _ not  _ stop talking about this brat. It was already a lot to handle when he just bragged about his bright intern, but now! Now, nearly  _ everything  _ Xeno talked about was about Senku. Which meant that Stanley knew nearly everything  _ about  _ Senku. 

He and Xeno were the types of friends that shared everything, after all. 

So when Xeno explained his frustrations of not being able to break Senku, well. Stanley was great at breaking things. 

Stanley leaned against the table, poking at the back of the boy's computer screen, "how much longer are your classes? You're not on webcam or anything, are you?"

“I just have to finish writing for this discussion… why? Do you need the kitchen or something?” He glanced over the top of his screen, an eyebrow quirked in curiosity. “I can move to the couch, I don’t mind.” There was a look in his eye that said no, he didn’t need the kitchen, but perhaps if he feigned innocence he could put off the man’s desires, whatever they may be.

Xeno had said this guy knew everything… there were more than a few definitions of  _ ‘everything’ _ . Surely he knew about all of Senku’s changes, if he knew about the regression, but how much did he know about what he and Xeno had been doing? Was he planning on getting in on it himself?

"Hmm," Stanley began - it was best to let him finish. While it was not a part of the rules he had been given, Stanley knew that Xeno would give him a hard time if he got in the way of the boy's academic studies. So he sighed, standing as he walked to the fridge, "don't worry about it, kid, I can work around you. Plane food fucking sucks, so I may grab a bite to eat," he glanced back at the boy, nodding towards the computer with a small smirk, "when you're all finished, we can get to know each other better. We'll be spending a lot of time together, after all."

Senku nodded a little and went back to his work, the only noise from him being the quiet clicking of keys as Stanley searched through the kitchen. His mind wandered and his typing slowed a little as he wondered absently what ‘getting to know each other’ entailed. He tried to remember whether or not the neighbors would be home right around now, just in case.

Stanley dug into the fridge then, sighing when most everything he found was health food, and eventually grabbed an apple from the counter before heading towards the living room, " _ never mind _ \- Xeno's food choices are just about as shitty as the airport."

“I’m way too aware of that.” Senku rolled his eyes, empathizing over Xeno’s obsession with health, probably made even worse by Senku’s ‘growing’ state. He debated offering some of the food he had gotten when he had gone to Japantown, but he had worked hard to earn that.

It didn’t take too much longer before he closed his laptop, then leaned back and stretched. He got up and made his way to the couch, dropping himself on the unoccupied end.

Stanley was absentmindedly browsing the television when Senku finally made his way over, noticing most things added to the recent 'lists' on the streaming services were all documentaries or, oddly enough, some cartoons. He was used to Xeno only ever wanting to watch the most boring of shit. But the cartoons were new - it must have been the kid. 

_ 'Kid'.  _

At least his small frame would make this easier. Still, Stanley didn't expect him to be so damn small, even for his age. It made him feel a little bad. 

Just a little, though. 

Stanley debated which approach was best, but in the end he knew that there was no real point in beating around the bush - it wasn't as if this boy would just give in to promiscuous flirtations. If that was the case, Xeno wouldn't be having such a hard time. So, with a sigh, Stanley stood, taking a few steps to get closer to Senku, seeing already that the boy was on guard. Rightfully so.

"I guess we can get to know each other, now," Stanley began, moving quick, knees on the couch near Senku while two hands grabbed at the boy's wrist, pinning them to the arm of the couch. It caused Stanley to loom over Senku, the dog tags falling from his shirt and dangling in front of his face. "Xeno tells me... you have a real hard time putting out. Is that true?"

Senku glanced up when his ‘guest’ stood, only to let out a yelp as he was quickly manhandled into a vulnerable position. His eyes darted between the man’s eyes and the shiny silver tag dangling in front of his face. At least he knew his name.

“…I-I can scream, and someone will come help.” He tried to still his gaze, not wanting to show the fear that was stirring in his stomach. “Let go of me.”

Stanley's grin grew. So he was a fighter - Xeno had warned him about that. "You can try - go ahead. But you'll lose the ability to talk afterwards." Stanley leaned in close, his dog tags falling against Senku's chest, bringing one hand down to run fingers across Senku's lips, "I'll duck tape your lips shut, turn on some loud music. Or, you can be an obedient little thing and I'll leave your mouth alone, so I can hear what pretty little sounds you make." The hand now grasped at Senku's jaw, keeping his face in place as Stanley moved his own closer, breath hitting Senku's lips as he spoke, "tell me - has Xeno even kissed you yet? Or am I here to take more than just one type of virginity?"

Senku’s lips immediately pursed, his face flushed bright red as Stanley spoke. Was screaming really worth it? Even if someone came to investigate, any cries could be explained away by Senku not being quite right in the head, none of the neighbors had actually met him, so it wasn’t impossible.

“…no, he hasn’t.” His voice was suddenly much more quiet and timid, knowing that Stanley was listening so intently, ready to take advantage of anything he said. “B-but I’ve already kissed someone, so you don’t… you  _ don’t  _ get to have that.”

" _ Ahhh _ ," Stanley's eyes closed as he shrugged his shoulders, "well that's a bummer. But was it a real kiss? Did you use any tongue?" Stanley's grip on Senku's jaw didn't falter, a single long lick running across the boy's lips, "you can say yes, even if it's true, I won't believe you. But aren't you lucky? Having someone experienced to teach you." His grip changed now, forefinger and thumb holding Senku's cheeks, forcing him to pucker. Stanley looked down at the boy with a narrowed stare, "I'll let you know now. If you even  _ try  _ to bite me, I'll make sure you regret it. Xeno never told me I couldn't hurt you." 

Senku whimpered quietly at Stanley’s grip, sure that he’d have bruises from it by morning. He wanted to come up with some kind of retort, but any sentient thought let his mind in a panic, and his voice would go unnoticed anyway.

Before Senku could answer, Stanley forced his mouth to pull open with a yank to his jaw, invading the boy's mouth with his tongue, both of his hands soon moving to push against Senku's shoulders. Stanley didn't even need to use all of his strength, just his weight alone compared to Senku was enough to disable him from moving away.

All Senku could do was let out a pathetic yelp as his mouth was forced open, and he tried to push his attacker off to no avail. He ran on instinct, scratching and kicking at the bigger body, making no dent in his drive or muscle. In an attempt to bite despite his warnings, he mostly bit his own tongue, prompting another squeal of pain and an iron taste to fill his mouth.

The sudden yelp of pain caused Stanley to pause - but that taste that hit his tongue was what made him pull away. He licked softly at his lips, staring down at the boy, "you tried to  _ bite  _ me. Even  _ after  _ I warned you." He sighed then, though nothing about it seemed actually upset. In fact, in a way, Stanley seemed excited about the act of deviancy. "Have it your way then, kid. You seem like the type that'll only learn from extreme measures, anyway." 

Stanley stood then - but before Senku could manage to squirm away from the couch, Stanley was roughly taking his shoulders and ripping him from his seat, only to shove him face down onto the couch. His hand stayed at the back of Senku's neck, keeping him pinned as he crawled over him, straddling his hips and keeping him there. He undid his belt then, but he had no intention on fucking Senku yet. Instead, he pulled the boy's hands behind his back, looping the belt tight around his wrists, managing to secure it. It wasn't the perfect binding, Senku could probably find a way to get out of them if given enough time. But Stanley wouldn't give him the chance. 

Stanley stood then, fingers hooked into Senku's sweat pants as he began to pull them from him, an easy feat even though Senku's legs continuously tried to struggle and kick at Stanley's body and arms. "See, kid, you're just proving to me more and more that you can't be trusted to be calm, jeeze." The drawstring from Senku’s sweatpants would do just fine; Stanley pulled the long string from the waist, using it to bind Senku's ankles together as well. 

"There," Stanley nodded to himself, standing as he looked Senku over, now only in his underwear and shirt. He knelt then in front of the couch, giving a few soft pats to Senku's cheek, "now - remember what I said about screaming. I know where Xeno keeps the duct tape."

Senku’s eyes widened as he was manhandled into position, only managing to fight back after a few moments. The leather and cotton cord bit into his skin, prompting a small hiss, but he still kept his mouth shut for the moment. Small tears pricked at his eyes, and he glared back at Stanley, but it was again more of a pout than anything compelling or intimidating.

“I h-hate you…” He mumbled, squirming against the binds. “I’m g-gonna… get back at you. And Xeno… y-you’re  _ both  _ awful…” He took a shaky breath, trying not to let any tears fall down his cheeks.

Stanley hummed softly, shrugging a bit, "yeah, we probably are. Just make sure your revenge plan is worth it." With one more pat to Senku's cheek, he stood fully, stretching before walking away from the couch. "Xeno said he had a box of stuff in his room that we can use. Isn't that nice of him? He even supplied us with goods to have fun with." He was gone soon, unable to be seen from the couch at all, but before Senku could even try to wiggle himself out of his binds or off the couch, Stanley was back with the box, dropping it onto the ground near the coffee table. 

"Let's see... what exactly that guy thought to buy," Stanley paid no attention at all to Senku, rummaging through the contents of the box. He gave a small " _ the hell is this... _ " to the speculum, dropping it right back into the box, shaking his head softly as he figured it was just some weird medical crap that Xeno decided to buy. But soon, his face lit up, grinning as he placed a few things onto the table. 

Lube, always nice. Next to it came a small pink box, the image on the front a purple vibrator with a rabbit-shaped appendage coming from the middle. Another box, this one claiming to be a 'G-spot Stimulator'. It didn't end there though, a small bullet vibe coming next, as well as a simple non-vibrating dildo, Stanley bending it and letting it flick back, testing its flexibility. "Damn, he really went all out. You have a big selection! Well, then," Stanley looked to Senku then, "how about I let you pick. You have thirty seconds - if not,  _ I'll _ pick."

Senku stared at the boxes as Stanley placed them on the table. He had seen them before, on the day they arrived in the mail, but it was much worse seeing them in this context. It was almost terrifying now, knowing that Stanley was likely going to end up using all of them. 

“The… the small one.” He wanted to point, but he tried to nod at the bullet vibe. He figured it would hurt the least as the first thing besides fingers to enter him.

Stanley let out a laugh - of course the brat would pick that one first. Oh well - once he was nice and prepped, Stanley would move on to more entertaining things. He grabbed the bullet vibe, moving away from the box and tugging at Senku's legs to bend them back, flopping himself down on the couch right beside Senku, letting his legs fall onto Stanley's lap. "I suppose first thing... is getting these pesky things off," he began, fingers hooking into the hem of Senku's underwear and pulling them down, bunching at his ankles due to his confines. "Now then, lets see this magical pussy of yours." 

Stanley grabbed either side of Senku's hips, forcing him to raise his ass high, and immediately Stanley let out a small awed chuckle. "Holy shit, he wasn't lying about this, either," without any hesitation or warning, Stanley pulled at Senku's folds, forcing his lips open to reveal the sensitive pink skin within. "You sure you were a boy before? You both aren't just fucking with me?"

Senku buried his face in the couch cushions, trying to keep himself silent. He didn’t want to give Stanley the satisfaction of any of his noises or reactions, but a few small hisses, gasps, and whimpers, managed to make it past his lips. 

“Y-yes, I’m sure. Believe me, I would much rather not b-be like this…” He mumbled, gripping at the fabric of the couch to keep himself grounded. He wanted to kick again, but he also wanted to avoid further confinement. “A-and I’m still a boy! This is just… t-temporary.”

Stanley sucked in some air through his teeth, "I dunno, this doesn't look very  _ temporary  _ to me. Then again, what do I know?" Stanley's thumb began to run down the folds, poking against the small clit, "I'm far from some scientist, and I don't think Xeno is the type to pull stupid tricks." With a shrug, though unseen by Senku, Stanley grabbed for the bullet vibe. "Ah, well, we aren't here for that, are we! You're gonna have a really, really long afternoon, kid. Xeno ain't off work for a few more hours." 

A small box was connected to the bullet vibe with a thin wire, a few buttons on it showing the strength of the vibrations. He put it on the lowest one, feeling it come to life between his fingers, licking his lips as he grinned and pressed the small pink device right against Senku's clit. "Bet this is your first time feeling something like this. You ever play with this stuff when you had a dick?"

Senku squeezed his eyes shut, trying to mentally prepare himself, but he couldn’t help the squeak that escaped his mouth before he bit down on the pillow below him. He had only heard one click of the button, surely this was just the lowest setting, but he was already whimpering and shaking at the sensation. As much as he wanted to retort, he didn’t trust himself not to moan if he opened his mouth.

"Oh? Nothing to say? That bothered already?" One more click, second level. Stanley now moved the bullet in a circular pattern across Senku's clit, a smirk tugging at his lips as he noticed the way the boy's hips and knees began to jerk. "So sensitive - I'm gonna say your answer is 'no', you've never played around with a vibe before," a few more circles, the bullet now moving higher, teasing Senku's entrance, a clear fluid beginning to eagerly fall from the hole. 

Senku let out a tiny whimper as the vibrations increased in intensity, immediately hiding his face in the cushion. His body, unfortunately, moved of its own accord and gave away his inexperience. It would be obvious even if he didn’t move though, the muffled noises and the wet between his legs was enough to figure out just how unused to this he was.

" _ Shit, _ " Stanley let out, chortling before pulling the vibe away entirely, "you're acting like you hate this, but you're already gushing. Well, I guess that makes this part easier..." Stanley brought it back, pressing it at the very center of Senku's heat, the most simple push able to send the slender bullet right past Senku's barriers and deep into his body. "And, ah, why the fuck not, right?" Stanley said it before pressing his finger against the buttons on the small box, sending it from the low level two and all the way up to a ten.

Senku’s entire body tensed up as the bullet was pressed into him, and he let out a barely audible squeak, which turned into a satisfied moan that he bit down on the cushion to muffle as the vibrations were turned up. Senku hadn’t even masturbated that much before his transformation, so now with the motor inside of him causing him to feel tremors through his whole body, he practically melted.

"Damn,  _ already  _ gone do it?" Stanley's fingers drifted down now, pinching at the swollen clit, tugging softly on it, watching how the added stimulation only brought more jerks and muffled moans from Senku's body. "And this is just some little bullet... you really  _ are  _ a virgin." Stanley gave a snicker then, looking at the other toys on the table. "Ahhh, imagine then, what one of  _ these  _ would do to you." A smirk played on his lips - a quick idea forming. "Actually, let's try something." 

Stanley reached forward, grabbing the box of the purple vibrator. Once opening it up and fishing out the silicone toy, Stanley gave a roll to his eyes, "of course he got one that needs batteries," a sigh left him as he stood, giving a single pat to Senku's ass before walking off into the kitchen. After a few drawer and cupboard inspections, Stanley finally came back with a few batteries in hand. 

"Let's get you comfy, first," he said, tugging a bit at Senku's arms, twisting his body until he laid on his back, arms still bound beneath him. "There we go. How are you feelin' down there? Close at all?" He didn't wait for a reply, bending Senku's legs up high again to take a seat in the middle of the couch, letting Senku's legs fall back onto his lap. "Gonna be a lot harder to muffle your little moans now, huh? I'll give you a short break, let you catch your breath before the big guns..." 

Lifting Senku's legs again, Stanley grabbed at the cord of the bullet vibe, giving a gentle yank and pulling it out from Senku's heat, a long string of fluid still connecting the toy to Senku's entrance. "Damn, you really  _ were  _ enjoying that."

Senku tried to keep more noises from escaping as he was maneuvered into another position, only letting out a small whine when the first vibrator was pulled from his walls. He pouted at the comment, mumbling out a “shut up…”

His eyes drifted to the next toy, it was bigger, but still not as big as he was when he still had a cock, so surely he’d be able to take it just fine. But the way he’d reacted when that tiny one was inside him was discouraging, considering this one was twice the size, and had another appendage that would likely go against his clit… he was going to have to work that much harder to stay silent.

The small retort from Senku only brought a quick laugh from Stanley. "I won't go full blast on this one, think ya'd pass out," with the batteries now inside, Stanley tested out the first setting with a single button click, making it slowly start buzzing in his hand. It wasn't too bad at all, and supposedly it went up six more levels. 

Leaning forward, Stanley grabbed the lube from the coffee table, "as wet as you are, I don't think you can take this without a bit of help..." He popped the lid, letting a good amount fall onto the toy, "how many fingers have you taken max? My guess is two," he said, pushing at one of Senku's knees, forcing them open - though not too wide, seeing as his ankles were still bound together. One of his hands spread at the folds, while the other now aligned the toy against Senku's entrance. Stanley had turned the vibrations off, wanting Senku to be able to focus solely on the sensation of the slightly curved toy, "this is a lot more than just two fingers... So make sure to give me some good faces and noises, yeah?" 

Senku never took his eyes off the toy, still regarding it with distrust. It would likely hurt, and the vibrations seemed to be more than the previous toy's, but it's not like Stanley was going to care. "Y-yeah, I think it was two..." He mumbled, muscles tensing in anticipation when Stanley turned the motor off and lined the firm silicone up against his entrance.

It took a bit of force, Senku's body definitely not used to the size, but the lube helped greatly as Stanley pushed the toy deep, slowly, as far as he could go until the toy finally seemed to reach a barrier within him. It could have gone more - but Senku's depth was obviously pretty small. But it still worked out just fine, the small cilt-stimulator on the base laying right against Senku's clit. With a dark grin to his lips, Stanley started the toy.

Senku let out a small whimper as his walls were stretched farther than he thought they could. He made an attempt to regulate his breathing, soft puffs of air leaving his parted lips, finally punctuated by a soft gasp when he felt the toy bump up against his cervix. He held his breath for a moment, before letting out a yelp when the vibrations were turned on.

The yelp caused Stanley's grin to grow, letting go of the toy and letting it be held in simply with Senku's muscles. He gave a pat to Senku's inner thigh, as if to tell him he was doing a good job, before leaning back against the back of the couch, "well, while you're having fun, I was thinking..." 

The television remote was sitting on the couch cushion near them, left there from when Stanley was browsing the channels before. He grabbed at it, one of his legs raising to rest his foot on the coffee table, the other soon crossing over it, switching the television on. He had a hunch that, while this kid seemed to be very similar to Xeno, the recent cartoons that had shown up on the  _ 'watch again' _ sections were not from his friend. As if to make it more obvious, as Stanley clicked on the cartoon with the strange looking blue cat thing, the episode that began playing started off with a Japanese theme song, subtitles beneath it showing the translation. 

"Ahh, this must be your sort of thing, then" his hand came down, laying on Senku's lower abdomen, not able to feel the vibrations through his body but perhaps with a few more levels... "Let's watch an episode together - could be fun. The hell is that thing, by the way? The blue thing."

Senku bit down on his tongue to keep any more noises from coming out, just light panting as he tried to get used to the rumbling deep within him. It was difficult though, he felt like his pelvis was being shaken, and like his legs were going to go numb at some point. He closed his eyes, trying to focus on something else. Counting, it was normally how he grounded himself, so maybe he could just count the seconds until this was over.

That was, at least, until an all-too-familiar theme song came on the speakers. He cautiously opened one eye, before shutting it again. He didn't want to associate his favorite character with this. "J-just turn it to s-something... something else..." He whined, turning his face away from the TV.

"So this  _ is _ a favorite of yours, good to know." Stanley made absolutely no effort to change it, letting the theme song play through entirely. Eventually the episode itself began, the odd blue cat-like creature talking to a young boy. It definitely seemed like a show for kids, which of course made everything happening feel even more unnatural. "If you can't answer my question, though..." 

Stanley's hand slipped between Senku's legs, holding the toy within his fingers and pressing one of the buttons, the more intense vibrations already being felt even through it's base. "We'll watch an episode together, just us two. Either the episode ends, or you come first." Stanley was sure to rock the toy softly, pressing the outer bit harder against the boy's clit, "though, you don't seem to be showing any issues giving in now. Does having a cunt make you a slut, or was this always some hidden part of you?"

" _ Sh-shut up _ ! I'm n-not a slut!" Senku made an attempt to kick at Stanley, but of course it was dampened by the cord that bound his ankles. "I-I just... I have some level of self preservation, you know." He pouted, before burying his face in the back of the couch once again. His words were punctuated with whimpers, and slight, subconscious bucks of his hips in an attempt to gain more friction on his clit.

"He, um... his n-name is Doraemon... a-and he's... a cat robot f-from the future..." His explanation was muffled by the fabric of the couch, in an attempt to hide his shame both from finding what he decided was a tiny amount of pleasure in this experience, and from enjoying such a childish franchise.

Stanley couldn't wipe the grin from his face, but Senku's pathetic denial in how much his body was enjoying itself. He never let go of the toy, which allowed him to slowly pull the toy out before ramming it right back in. "He's a cat...?" Stanley asked, doing the action once more, "kind of a weird looking cat, he doesn't even have ears..." Stanley glanced down then, seeing Senku's face tucked into the cushions, a sight that made him immediately let go of the toy. 

"Ah ah - hey," the hand reached over, sliding beneath Senku's cheek and forcing him to turn his sights to the television, "none of that - we're watching this  _ together _ . Now, tell me about the boy. He have a name?"

Senku whined as he had to reveal his splotchy red face, his eyes puffy with tears. Maybe if he kept talking, he could distract himself from the sensations that came from his core, and he could avoid any other embarrassing noises as Stanley moved the toy.

"H-he had ears, but a m-mouse chewed them off..." He dug his nails into his palms, again trying to distract himself. "The boy's n-name is Nobito... he's really s-stupid but he helps D-Doraemon..."

" _ Uh huh _ ," Stanley's hand hovered over Senku's face for a moment, making sure he wasn't going to immediately turn his head back into the couch. When he didn't, Stanley brought his hand back to the toy, giving it another few good thrusts into Senku's body, being sure to press up again on the vibration levels. "And what - they go on some magical adventures or something?" If Stanley had to be honest, he had no real interest in the show at all. He had not even read the subtitles at all since beginning the show, his attention instead focused on the way Senku's chest rose and fell with growing speed. "Hey - kid, if you're close, tell me. Don't want you trying to fake an orgasm or anything."

Senku let out a gasp with each thrust, increasing in volume as the vibrations grew in intensity. "N-no, they go on s-scientific adve-entures..." He whimpered, back arching. He wasn't sure how to warn Stanley of an oncoming orgasm, he still wasn't sure on how they really felt with his new parts, since he'd only reached a climax twice since his transformation.

"Ahhh - of  _ course  _ it's science related. Xeno watch this with you at all?" Stanley figured the answer was probably no - Xeno was never really the cartoon type, even when they were kids. "Guess you have a childish quality about you then - heh - that's  _ cute _ ". He glanced down to Senku then, an eyebrow raising as he watched Senku react to each and every thrust. Stanley's smirk grew - he wasn't even going that hard! 

Stanley began to bite at his bottom lip - it was becoming hard to keep himself off the boy, the throbbing in his jeans strong enough to nearly make him lose control. But he wanted this to last longer than a single quick fuck. They had the entire afternoon, after all. He'd let the boy rest, here and there, but by time Xeno game home, he'd make sure the boy had  _ experience _ . 

Senku's breath was getting not only faster, but shorter eventually, making Stanley raise an eyebrow. "Hey - hey, what did I tell you?" Giving a groan, Stanley turned on the couch, sitting to face Senku more properly. "I don't want you faking shit to try and get out of this faster." He pushed at Senku's legs then, sending the boy into a crunched position, removing the toy with a sick grin, "damn, making a huge mess on the couch. Xeno's gonna be pissed at you." 

With the toy out, Stanley wasted no time in forcing his fingers inside - three of them, made easy by the loosened walls and slick fluids leaking from him. He didn't turn off the toy at all, using the tip to rub directly against Senku's clit, his fingers already curling as they began an insanely fast pace repeatedly into his body. "If you're gonna cum, I want to feel it, understood?"

Senku let out a pitiful whine as Stanley removed the toy, mumbling something incomprehensible in response to the cocky remark, only to be interrupted with a yelp. The sensation was already enough with just the toy inside him, but with the vibration against his clit and the fingers practically hammering against his walls, he let out a sob. His hips canted up and his panting was interspersed with whimpers and whines. It felt far too long until he came, though it was only a minute or two when he tightened around Stanley's fingers and let out a high-pitched whine.

_ There it was _ \- Stanley could feel it, Senku's body absolutely giving in to the pleasure, a series of spasms causing him to clench around his fingers, nearly sucking his fingers in even further. Stanley had to hold in his own small noise, an open-mouthed grin showing his gritting teeth, but luckily Senku's loud moans greatly out shined him. He was gasping out, shaking, totally unaware of how fucking hot his body looked going through its peak. Stanley was sure to keep the vibrator rubbing against his clit for a small time, but eventually removed it once Senku's body finally stopped tightening around his fingers, turning it off as he let his fingers fall from his sex. Long strings of fluid connected his fingers to Senku's folds, dripping down to add more mess to the couch. It would be fine. It wasn't like Xeno told him he couldn't ruin the furniture a bit. 

Stanley sat the toy down on the other side of the couch, letting Senku's legs drop lifelessly onto his lap, his hand now wiping away the fluids from his fingers by cleaning it on Senku's shirt. The boy seemed entirely out of it... Stanley soon giving a small pat to Senku's chest, "still lucid down there?"

Senku let his head fall back and he panted while trying to regain his breath. He shot a weak glare over at Stanley, his lip curling in an attempt to be intimidating, but it probably didn't work. "F-fuck you..."

He thought back to what he felt like as he neared his orgasm, everything was tense, all his muscles tightening, before he finally relaxed and gave into the mind-numbing pleasure. He'd have to remember that for later, maybe he could stop himself next time.

" _ Fuck _ me?" Stanley began to chuckle, "well damn kid, I already plan on letting you get a taste of that, but" Stanley's hands sunk back between Senku's legs, finding the boy's tired clit with his thumb. His pressure was hard, rubbing against the swollen nub vigorously, knowing full well it would overstimulate the boy, "you really,  _ really,  _ need to work on talking back to your superiors. You have no say in what's happening right now. You should be  _ thanking  _ me."

Senku let out a high pitched whine, his thighs quivering at the stimulation. "Y-you're  _ not _ ... I don't ha-ave to respect you..." He mumbled, trying to kick despite his still-tied ankles. "B-bastard..."

Stanley's eyes began to narrow, "you're talking a lot of tough game for someone who just turned into a little bitch." He grabbed at the boy's ankles, undoing the cord that held them together, but only to be able to force Senku's legs wide as he situated himself between them. Pulling at Senku's thighs, Stanley was able to grind his hips into Senku's core, enjoying the friction and pressure on his throbbing bulge. He needed a lot more of that, but unlike the brat beneath him, Stanley had more control. "You were bucking your hips into the toy and my hands, you wanted  _ more _ ." 

His face moved down, pressing his nose into the crook of Senku's neck, lips sliding along the flushed skin, "if you just admit you're a slut, I'll let you have control of your arms while I fuck you."

"I-I'm not!" Senku glared up at Stanley, tears pricking at his eyes. "I d-didn' want it..." His breaths were shaky, and while his arms were starting to cramp, it was far less pain than giving in to what Stanley wanted. "I h-hate you..."

Stanley gave a hum into Senku's neck. Xeno was right - this kid wasn't giving in easily, despite how much his body was enjoying the treatment. "All right then - have it your way." He pulled back entirely, but not before grabbing at Senku's shirt to yank the boy forward, "we should definitely move somewhere with more room, though." 

Stanley stood from the couch, Senku's small frame more than easy to lift up and toss over his shoulder, supporting the boy's ass as he began to walk away from the living room. He didn't bother to turn off the television, letting the Japanese cartoon show play on in the background, heading straight towards Xeno's bedroom. Once inside, he shrugged Senku off of his shoulder and right onto the bed. 

Senku continued to struggle on the way to the bedroom, mumbling inaudible hatred for Stanley and letting out a squeak when he was tossed onto the bed. He immediately closed his legs in an attempt to cover up his still-wet sex.

"This would all be so much more enjoyable for you if you just admitted you liked it, you know," Stanley began to undo his pants then, not yet bringing out his cock, leaning one knee down onto the bed as he loomed over Senku's frame, "how about this - call me  _ 'sir'  _ and I'll go back out and get more lube. Or you can tell me how much you hate me and I'll go in raw."

Senku weighed his options silently and carefully, his glare never leaving Stanley's face. Sure, he was already soaked, but he wasn't sure if that would be enough for a larger intrusion.

"F-fine...  _ sir _ ..."

A big grin grew on Stanley's face, "don't much like your tone, but I'll take it." He was gone out the door, but moved fast in grabbing the small bottle from the living room, back into the room within seconds. "Honestly, Xeno probably would have killed me if I tore you, so you chose good for both of us. I'll make sure to make you feel  _ really  _ good, in thanks." 

Stanley crawled onto the bed now, pushing Senku's legs wide as he situated himself between them. It was then that he finally pushed down his pants and boxers enough to release his cock, letting it lay against Senku's stomach, a soft sigh leaving his lips as he stroked it slowly, noting the size difference now between his body and Senku's. His length easily reached past the boy’s belly button. "Damn, really hope that toy stretched you enough. Ah, well, the lube should help."

Senku's eyes widened as he stared down at Stanley's cock resting upon his stomach, and he chewed at his lower lip. The head definitely reached farther than the barrier inside him, and he swallowed nervously. "No way that's going to fit..." His eyes flickered back up to Stanley's, still with a layer of concern. "And... a-aren't you supposed to use protection?"

"Hmm? Aren't you  _ 'too young' _ to get pregnant?" Stanley held his cock in his hand, stroking it a few more times as he began to press the tip to Senku's entrance, eyes fluttering for just a moment at the sensation of Senku's wet heat. 

"W-we don't know yet..." Senku clenched his fists, his nails sure to leave marks on his palms.

Stanley gave a small shrug. "Well, I don't have any on me... and, it'll fit. _ I'll make it fit _ ." The lube - he couldn't forget that, taking a moment to drop a good portion into the palm of his hand before coating his cock in the cold liquid. 

Stanley began to press the tip of his cock once again at Senku's core, his eyes closing and letting out a small sigh as he finally put enough pressure for his head to sink deep into Senku's body. He was maybe only an inch in, but  _ god  _ Senku's walls were constricting around him. Gritting his teeth, Stanley's hands began to rub at Senku's hips slowly, "shit, you're fucking tight... you need to relax."

Senku let out a high-pitched whine as Stanley pushed in, immediately clamping down on the intrusion. Stanley was definitely bigger than anything he had taken before, causing him to squeeze his eyes shut, more tears falling from his eyes.

Senku wasn't relaxing at  _ all _ , but Stanley wasn't letting that stop himself. He slowly began to press himself deeper, leaning himself over Senku's frame, hands slowly slipping beneath Senku's body. It was a bit hard to do it as Senku was lying, but Stanley managed to undo the hook of the belt that bound his wrists. Eventually he was able to slide it out from under him, letting the belt fall into the blankets. "There, you can move around a bit more now." 

Even though Senku's hands were free, it didn't stop Stanley from entirely enveloping the small boy with his much larger frame, holding him close as he began to lick at the tears that fell from his eyes. "You feel  _ really  _ fucking good" Stanley whispered out, his lips pressed against Senku's cheek, hips now sliding out his cock before ramming it back in - able to feel Senku's most inner barriers stopping him from being able to fully enter him.

With his hands finally free, Senku immediately wrapped them over Stanley's shoulders, gripping and scratching at the back of his shirt. It hurt, it hurt so  _ fucking  _ much, he wanted to make sure Stanley felt some of it too. 

There was a steady stream of tears now, and he let out a yelp each time he was filled. He wouldn't be surprised if he was bleeding, but all he could do was continue to scratch at Stanley's back, and whimper out incomprehensible mumbles of " _ IhateyouIhateyouIhateyou _ ..."

Stanley grinned wide, beginning to nibble on Senku's earlobe, "say that all you want, kid, it'll just end up making me go harder." To prove his point, Stanley's fingers began to dig into Senku's hips, holding them in place as he began to ram harder into him, not bothering too much with getting the boy used to the sensation. 

"Here..." Stanley breathed it out, grabbing at one of Senku's arms. The boy was trying so hard to grip and scratch, but it wasn't doing all that much damage at all with Stanley's shirt acting as a barrier. He leaned up for a moment, grabbing at the hem of his shirt before lifting it off of his body, letting it fall onto the bed aside the belt. "There," he said with a grin, leaning back down and giving a small bite to Senku's bottom lip, enjoying the glare he got in return. "Go ahead, mark me as much as you  _ think  _ you can."

Senku let out another cry at the increase in force, but was at least grateful that he was given permission to fight back as much as he wanted, taking the opportunity to bite down on the skin of Stanley's neck, and scratching his nails, ragged from chewing them short, up the man's back. Even if Stanley didn't care, even if Stanley liked it, Senku could at least show his anger.

" _ There you go _ ," Stanley purred it out, returning the favor by leaving small bites along Senku's neck, sucking hard on the skin in a few places to leave immediate red and bruised marks. His hand soon dropped down, thumb able to run slick against Senku's clit with how wet the boy had become. "You can keep denying it all you want," Stanley whispered it right into Senku's ear, giving a good harsh thrust and letting himself stay buried for a few seconds, "how does it feel? Your virginity going to a complete stranger?" Small bites now landed on Senku's earlobe, tugging on the soft skin, "Xeno  _ wanted  _ to fuck you, I'm sure he would have treated you so much more delicately your first time."

Senku stared up at the ceiling as he contemplated Stanley's comment, still absently chewing at his shoulder both in thought and to show that he wasn't going pliant. "Th-this isn't my first time..." He grumbled, again curling his nails into Stanley's skin. 

It was true, at least partially. He and Taiju had experimented when they were younger, but it was never penetrative. The farthest they had gone was frotting against each other, or Taiju stroking both their cocks in one hand.

Stanley's movements began to slow, staring down at the boy. It wasn't exactly easy to tell if someone was lying when you were, quite literally, balls deep inside them. But even so, the mumbling tone and the fact that Senku could not look him in the eye just made Stanley laugh. "Okay,  _ sure  _ kid.  _ Whatever you say _ ." He slowly pulled out once more, giving another hard thrust into Senku's heat, "let's...  _ say  _ you're telling the truth. And let's  _ say  _ I believe you," one more hard thrust, Stanley's hand gripping at Senku's waist and aiding in pulling the boy even more flush against his hips. 

The hand now slid upwards, delving into Senku's hair, gripping hard as he yanked the boy's head to the side, running his tongue across his entire exposed neck until he met Senku's ear. "This is the first time you've had a cock inside your hungry little cunt." He began to leave small kisses along Senku's jawline now, all too soft in comparison to the way his hips continuously pounded his small body into the sheets, eventually leaving colorful lipstick marks across the sides of Senku's mouth. "You'd enjoy it a lot more, if you would just admit that it feels good. Here -  _ I'll help. _ " 

Stanley took one of Senku's arms into his own, pulling it away from trying hard to dig nails into Stanley's back. Taking hold of Senku's wrist, Stanley forced the small hand downward, maneuvering Senku's fingers to slide across his clit. "Feel that? Have you ever even  _ touched  _ yourself before?"

Senku let out yelps and whines with each thrust, feeling as though Stanley was trying to break through his inner walls. He could keep insisting that this wasn't significant, but he'd be lying. He only wished he had the opportunity to imagine that Stanley was someone else that Senku cared about.

He couldn't stop his fingers from rubbing against his clit despite its sensitivity, it at least distracted from the pain that ripped through him each time Stanley tried to fit his entire length inside. He kept his lips pressed together, biting his own tongue to keep from letting out any noises.

"There you go, just like that..." Stanley let go of his wrist fully now, grinning as he watched Senku's hand almost desperately running his fingers in a fast pace against his clit. "Feels good, right? Ah..." His eyes now fell on Senku's thinly pressed lips, his chest rising and falling with a fast speed. Obviously the guy was trying to prevent himself from moaning out. He probably knew it'd cause Stanley to tease him even more. 

"Ah ah," Stanley continued the noise, reaching up now to tug at Senku's chin, but the boy wasn't opening his mouth that easily. So, with a quick laugh, Stanley ran his tongue across both lips, "I can tell you're wanting to call out. I don't mind, you feel pretty damn good yourself you know." Stanley moved back again to Senku's ear, not an ounce of shame in his voice as he let a moan out against Senku's skin. He kept it up with every single thrust, occasionally looking down to ensure that Senku was still teasing his clit.

It didn't take too much longer for Senku to notice his muscles starting to tense again, his breath quickening. He wanted to stop moving his hand, to scream loud enough for one of the neighbors to interrupt them, but all he could do was chase his sweet release. Finally, he let out a cry that he muffled by biting down on Stanley's shoulder, and his walls constricted around his cock.

" _ Shit-- _ " Stanley wasn't expecting him to come so  _ soon _ , wincing and gripping hard at the sheets as the boy's body became almost overbearingly tight. The bite was only heightening everything, a groan leaving Stanley's gritted teeth, his hips never slowing as Senku rode out the waves of his orgasm. "You're so fucking  _ fast _ ," Stanley panted out, not planning on stopping until he reached his own peak, giving a laugh as he noticed Senku not letting up on the pressure of his bite at all. "Don't worry, I won't stop..." Luckily, he could feel his own muscles beginning to tighten, a sensation that brought a sudden thought to Stanley's mind. 

"Hey," he spoke softly into Senku's hair, allowing him to bite for as long as he needed, "keep clenching like that... and I'll come deep inside you... or is that what you want?" God, he was close - if he could just hold out a few more seconds, enough to tease the boy some more, "I'll empty everything I've got into your brand new cunt, and we can test out if you can get knocked up."

Senku's jaw didn't loosen through the teasing, as much as he wanted to retort that of course he was fast, he was still sensitive from his first climax, but he didn't want to let out any accidental noises.

That was at least until Stanley's final sentiment. He rationally knew it was just teasing, that even if he did it, Xeno would be quick to reverse it. But even so, he let go of Stanley's shoulder and tried to push him off, any ounce of indignation gone from his voice as he babbled through his sobs. "No, no,  _ nonono  _ please don't  _ please– _ "

The pushing didn't bother Stanley too much, but he still grabbed onto Senku's wrists, pinning them both above his head. " _ So _ sorry," he panted out, though his tone was anything but apologetic. "Too close to stop now, you'll just have to bare with me," it was a total lie - even as Stanley was finally giving a few final deep thrusts into Senku's heat, he still had the ability to pull out if he wanted. He just didn't want to, making sure to moan loudly into Senku's ear as he finally reached his release, feeling his orgasm gush around Senku's walls and spurt from his hole, definitely too much for the small body to hold. 

Stanley stayed, panting for a moment, but was able to quickly recoup himself, leaning up and letting go of Senku's bruised wrists. Maybe he did the belt a bit too tight... He looked down to where their bodies met, slowly sliding out from Senku's body, a large collection of cum spilling out with him. "Ah..." Actually.  _ Actually  _ that was a bit of a stupid idea. "May have to call up Xeno and ask for some plan B, huh."

Senku didn't know the last time he cried, surely it was when he was younger, out of frustration when one of his prototype rockets didn't work. But now, as he felt sticky fluid leave his insides, his lip began to quiver and hot tears welled up as he started to sob. Filled with a new, panic-fueled strength, Senku started kicking at Stanley again, scrambling away from him. "G-get the fuck away from me! You  _ bastard _ !"

"Hey- hey! Alright!" Stanley did, in fact, get the fuck away, though there was a low chuckle from him as he did so. "The plan B stuff works as long as you do it within a day, you're going to be fine, jeeze." To further prove his point, Stanley took his cellphone out from his pants pocket, taking a quick moment to tuck his cock back into his pants before scrolling through his contacts. "Xeno gets off soon - I'll call and he can get some on the way home." He looked down then to the crying boy, his sobs far from just being a  _ bit  _ upset. A small part of him felt bad - he had all intentions on scaring the fuck out of the kid to prove a point, but perhaps the last part was uncalled for. 

With a sigh, Stanley ran a hand through his hair, waving the phone, "I'll call now, okay? You can... stay in here and cry and clean up or something, whatever you want." He turned from Senku then, scrolling the phone until he found Xeno's name, putting it up to his ear and walking out from the bedroom.

After a few minutes of crying into the mattress, Senku finally started to quiet down, tears continuing to surface but noises reduced to sniffs and whimpers. He got up on shaky legs and found a clean t-shirt and pajama pants, as well as a new pair of underwear, before slinking off to the shower to wash away all the dried cum and saliva that clung to his skin. 

As he washed himself off, Senku grimaced at the blood that had mixed with both his and Stanley's fluids, before quickly rinsing it all down the drain and resumed scrubbing at his skin with a washcloth.

Stanley could hear the shower going, the call to his friend finally ending. A long sigh left him, rubbing at the back of his neck. Xeno was rather short on the phone as Stanley told him to pick up the medicine on the way home, which meant one thing: Xeno was  _ far  _ from happy, and a pissed off Xeno was honestly something even Stanley knew better than to mess with. He figured he'd busy himself in the kitchen until Xeno got home, knowing he'd most likely get an earful when his friend would come through the door.


	7. Experiment 07

_ ‘Far from happy’ _ was putting it lightly. 

Xeno held a lot of trust in his childhood friend. And, while this was not something that would destroy the lifelong friendship, Xeno's blood still felt as if it was boiling as he exited the apartment elevator. He had bought the _ 'Plan B' _ medicine. The issue would be resolved. But that did not mean that he would forget the breach of trust that easily. 

As he walked into the apartment, a sudden smell wafted from the kitchen. Stanley must have been cooking, though Xeno could not tell exactly what it could be from smell alone. He closed the door, the sound being enough to alert his arrival, Stanley soon peeking out from the kitchen. 

Stanley's eyes locked with his, both of them knowing full well that the atmosphere in the room was tense. "Welcome home...?" Stanley spoke, and Xeno felt a sense of accomplishment in hearing that the tone of Stanley's voice was a bit on edge.  _ Good. _ Xeno was hoping Stanley would be dreading his return. 

Xeno took off his coat and placed his keys in the usual spot on the table near the door, walking more into the apartment, a bag in his hands. After a quick look around the open room, he gave an inquisitive stare to his friend. 

Stanley answered with a shrug, "he hasn't left the bedroom."

"I wonder why." Xeno's eyes closed as he sighed, a hand moving up to rub at the bridge of his nose, "Stanley, I only gave you a  _ few  _ rules to follow. All of them were very simple."

"I haven't smoked inside the apartment, I've been using the balcony." 

Xeno only stared blankly at his friend. 

With his own sigh, Stanley gave an exaggerated shrug, "look, it's not like I carry condoms on me at all times, I just got back from the fucking airport. Not to mention," Stanley stepped closer now, his voice much lower as he spoke with a sharp tone, "you're the one that asked me to come here and fuck your little protégé assistant in the first place." 

Xeno's eyes began to narrow, his hand reaching out and gesturing to the box that had held the items he bought online, "there were condoms in the  _ box _ , Stanley, if you had cared to check further." His head now gave a small tilt to the side, his stare turning judgmental, "I would think a military man such as yourself would be better at accessing the situation before charging in head first."

Xeno watched as Stanley studied his expression, brows furrowed before closing his own eyes, stepping back with a sigh. "Okay - all right. I'll admit, I may have fucked up." He turned from Xeno then, walking back to the food being prepared, "I'm making dinner, but I don't know how good it'll be since the only shit you buy is vegetables and whole grain stuff."

Xeno breathed deeply - Stanley was a hard person to get to apologize in the first place, but it wasn't Xeno who he owed the apology to, anyway. Though, knowing Senku, it would take a lot for him to ever accept it in the first place. Xeno reached into the bag, taking out the small box, glancing at the instructions as he walked towards the back room. He should also make Stanley pay him back for the single pill - it was  _ ridiculously  _ expensive. 

Xeno paused in front of his bedroom door. It was his  _ own  _ bedroom, and yet, he felt as if he should be knocking to gain access. He debated it for a moment, hand nearly raising to do just that, before deciding against it and slowly opening the door, his voice soft as he called out, "Senku...?"

Senku had retreated himself back to the bedroom once he thought he was sufficiently scrubbed clean, though of course he couldn't wash away the various bites and bruises left on his skin. He had gotten dressed quickly, not wanting to be exposed anymore, before stripping the bed and putting new, clean sheets and blankets on. Finally he curled up under the blanket, content to just sleep until Xeno got home. 

When he at last woke up, it was to the creak of the door and Xeno's voice trying to be soft and comforting. He opened his eyes, shooting Xeno an exhausted glare. It surely wasn't too intimidating though, since everything up to his nose was covered in blankets. "What?"

Xeno looked over to the mound on the bed, knowing full well that Senku would not care much about the concerned look he gave the boy, but Xeno still watched him with a face of worry. Did he want to break the boy...?  _ Yes _ . He would not have asked Stanley for the help if he did not have ulterior motives. But he did not wish to completely shatter Senku beyond repair. There would be no fun in a lifeless doll. 

Xeno walked slowly as he entered the room, as if to ensure Senku that he was not there to worsen the situation. He placed the medicine box on the side table, offering a small smile to the boy, "I will get you some water." He turned from Senku before he could answer, removing himself from the room as he went straight to the kitchen. 

Not a word was shared to Stanley as Xeno filled a small glass with some cold tap water. He would let his friend stew a little while longer. It was still unclear if this sort of experiment did any good in the end. 

Once back in the bedroom, Xeno placed the water down onto the table as well. He took a step back, waiting, intent on seeing Senku actually swallow the pill, to be sure that it was in his body and would be doing as it should.

Senku had sat up as Xeno was leaving, quickly grabbing the pill before sitting in place to wait for the water. As soon as Xeno set the cup down, Senku grabbed it and took the pill, washing it down with the whole glass.

When he was done, he set the glass back on the table, before laying back on the pillows and crossing his arms. "I-I hate both of you." He shot Xeno another distrusting look, "Bring me my Switch or my phone or something, I'm not going back out there."

Xeno slowly arched an eyebrow, but turned and left the room as Senku had requested. He found the boy's switch as well as his cellphone near the couch, taking a moment to narrow his gaze at the mess left on the couch. As he turned back towards the bedroom, Xeno made sure to call out to Stanley, "I expect you to clean up the mess you've made." 

Xeno was able to make out a  _ 'yeah yeah, I'm making dinner, I'll do it later,' _ as he entered the bedroom once more. He placed both items down on the bed, locking eyes with Senku as he did. 

"You cannot stay cooped up in the bedroom forever. You will eventually have to leave, for the bathroom, or for food. Stanley will not touch you while I am around." At least. Not without his express permission. But Senku didn't need to know that.

Senku narrowed his eyes as he took his electronics, before quickly looking away. "Whatever. I'm not letting either of you touch me." There was some nagging thought at the back of his head that he wouldn't be able to fight just one of them off, let alone both of them. But he didn't care about that for now... he could just leave when the both of them were asleep, and hope he made it back before they woke up.

Xeno stood, walking closer to the boy before taking a seat on the edge of the bed. He expected the way that Senku slowly curled his body - but he didn't call him out on it. His eyes began to dart over his body, trying to take in what he could see, but clothes had covered mostly everything anyway. Though, he was able to make out the brightly bruised hickies that covered Senku's neck. 

"Do you want to tell me what he did to you? It's best to talk about such things - get it out. It will do you no good to bottle it."

"I don't need to, and I'm sure it's pretty self explanatory anyway. You can go ask him if you want all the details..." He mumbled, turning his game system on. "I'm sure he won't lie about me hating it, he probably got off on it anyway." 

Senku curled up a little, quickly sending a text to Taiju and Yuzuriha, telling them to play a game with him, before glancing back up at Xeno with angry, glassy eyes.

Xeno had expected that much. He could push it, of course. Try and force the story from Senku, but Xeno was already mostly aware of what Stanley had done, given the mess out in the living room as well as the medicine he was told to buy. Though - one thing did stand out to Xeno as he watched Senku curl up with his game system and cellphone. His wrists, showing the signs of bruising from, most likely, a restraint. It was a gamble, but Xeno slowly held out his hands to the boy, brows furrowed as he look only at Senku's hands, "may I see your wrists, Senku?"

Senku furrowed his brow at Xeno, before sitting up and holding out one hand. "Why do you care? He said you never told him not to hurt me, so..." 

He winced a little as Xeno inspected his wrists, the pale skin already a blotchy purple-pink. His ankles hurt somewhat too, but since they were bound in a stretchy cord rather than tough leather, he didn't feel like it was that much of an issue.

Xeno was looking over the wounds, thumb running gently across the bruises and slight scrapes in the skin from constant rubbing and chafing. A small sigh left him at Senku's words, "I did not tell him he  _ couldn't  _ hurt you, but I also did not tell him  _ to  _ hurt you." Xeno still held Senku's wrists - there was an unspoken truth in the room that both he and Senku were aware of. Xeno had willfully allowed his friend, even encouraged him, to force Senku into sex. But it was important not to dwell on that. He needed to sway Senku's mind to something else. 

"You need not worry - this will not happen again. Stanley will not be allowed to touch you again without your express permission. I will have no say in it." He gave a few final slow rubs to the bruised skin before standing, walking now towards the door, "you should take something, for the pain." 

Senku pursed his lips as Xeno spoke, willing back tears at the implication of it all. Everything that his supposedly trusted mentor had done, and had let Stanley do. He nodded slowly at Xeno's promise, his lips parting slightly to ask, ‘ _ but what about you’ _ , only to find himself interrupted. He didn't have the energy to assert himself anymore.

Xeno disappeared through the bedroom door, away into the nearby bathroom, only to soon return with a small bottle of painkillers. "I am sure you are already feeling sore." Xeno placed the bottle of pills down near the glass of water, looking down to Senku, "I was informed... that you were not...  _ spacious  _ enough for Mr. Snyder."

Senku took two of the painkillers before settling back against the pillows, a light blush spreading across his cheeks at the comment. "Y-yeah, it ended up hurting a lot..." He left off the remainder of the thought, that for some sick reason he came anyway. If he didn't acknowledge it, it wouldn't matter, supposedly.

Xeno nodded slowly, "as to be expected. The painkillers will help," he glanced now, to the bedroom door, "it seems our guest is making dinner for us both, though I have no idea what it is, and I do not know Stanley to be too skilled at cooking, so if it is edible enough I will bring you a plate." He looked to the small glass on the table, now empty of water, leaning over to grab at it... but stopping, fingers tapping slowly at the rim as he leaned over the bed a bit more, nearing close to Senku's ear, "if it makes you feel any better, I am not ashamed to say that I am nowhere close to Stanley's size." 

He rose with a shrug, grabbing at the glass, "at least, as far as I am told. Stanley has always been quite boastful," he turned then, waving the glass as he walked from the room, "I'll be sure to bring you more water with dinner as well, unless you want to request something else."

Senku tensed at Xeno's whisper, but only managed a sneer. "Sh-shut up..." He mumbled, quickly turning his attention back to his game and taiju confirming that he was ready to play. "I... I'm fine with water. I can make my own dinner if his doesn't turn out good." He briefly wondered if Xeno had found his stash of ramen in his bag, if he had it was probably already in the garbage, but if not Senku could make it when both of the older men were asleep.

Xeno's smile only grew as he exited the room. A stutter and a quick _ 'shut up' _ was something Xeno could handle. It was far from the comments that Stanley would most likely get if he were to try and walk into the room. He brought the glass out into the kitchen, looking over the food that Stanley had been preparing. It seemed to be some sort of vegetable and pasta dish, the spices pulled down from the spice rack suggesting it would be very...  _ full  _ of flavor, perhaps almost too much flavor. 

Xeno said nothing to his friend, but nothing much needed to be said at the time. At least, not within easy earshot of Senku. Instead, Xeno moved his laptop to the dining room table, still needing to go over a few final emails before his work day was truly over. 

Eventually, Stanley sat at the table as well, a large sigh coming from him. "It's not much," he said, shrugging as he gestured to the plate of food, "honestly, no meat? Have you gone vegetarian?"

"Of course not," Xeno stood, walking to the cupboards to pull down two more plates, "I have yet to do food shopping is all. I have been... _ preoccupied. _ " 

"Too busy wandering around Japantown and locking kids in dressing rooms, hmm?"

Xeno paused as he was dishing up the two plates of food, turning to shoot a dark glare to his friend. But Stanley only met the glare with a low snicker, leaning his elbow onto the table as he propped his chin into his palm, "you have to tell me about that in greater detail, now, I'm dying to know. Think he'd wear the dress again?" 

Xeno turned back around, finishing plating the food, "right now? There is very little chance, you should know that. Perhaps in due time, but I doubt that time will be during your stay-  _ ah. _ " Xeno stopped, holding both plates in his hands, brows furrowing. "I do believe... I forgot to mention that..."

With a deep sigh of his own, Xeno left one of the plates on the dining room table, being sure to grab some more water before he made his way back into the bedroom, knocking softly on the door before heading in. He placed the water onto the side table and the plate of food at the foot of the bed. "I have failed to inform you earlier. Stanley will be staying with us for the next two nights."

Senku glanced up as Xeno came into the room, setting aside his game while Taiju and Yuzuriha continued to play around him. He sat up to grab the plate, only to pause at Xeno's words.

"... _ perfect _ . That's wonderful." He sneered, grabbing the plate and poking at it with his fork. "I already know you don't have a guest bed, so where's he going to sleep?" He looked up at Xeno with a darkly quizzical look, already knowing where Stanley was going to sleep, and not at all wanting to be near him.

Xeno stood straight, his hands folded behind his back, "in the past when Stanley needed to stay for short periods of time, he used the couch, where you are currently staying. And, well, now," Xeno glanced down to the bed. It was a king - large enough for the two of them, but he already knew based on the look in Senku's eyes that he was not going to appreciate the offer. "You seem to have taken quite the liking to hiding out in my bed, which is where I will obviously sleep. You are welcome to share it, for the next couple nights."

" _ Absolutely not. _ " Senku narrowed his eyes, "I'd rather sleep in the bathroom or something. I don't care if he's 'not allowed' to touch me, and  _ you  _ certainly didn't make any promises." it wouldn't be comfortable, but at least it had a lock on it, and he would have everything he needed until morning.

Xeno only gave a shrug to his shoulders, though a smile began to play on his lips. He had expected as much. "You may do as you wish, you know where to find the spare blankets and pillows, and the bathroom does have an outlet, so I suppose you will be content enough." Once again, Xeno turned to the bedroom door, allowing Senku to continue his hiding away. "The dinner should be palatable enough. Though, I do wonder if having to eat army rations have destroyed my friend's taste buds. Ah, well, " he turned his face back to throw a smile to Senku, "if you change your mind about wishing to share a bed, just let me know." 

Xeno walked from the bedroom then, back out to Stanley who seemed perfectly happy with what he managed to make. Xeno sat down across from him at the dining room table, both of them sharing a single look that meant enough for now - they'd talk more extensively later. For now, Xeno looked down to his food, wondering if perhaps he should order for take out later on. 

* * *

Stanley was already setting up on the couch as Xeno finished up a few final things on his laptop. His friend had stated that the jet lag was hitting 'like a bitch', and he was planning on passing out the second he laid down. Though, Xeno couldn't help feel a bit of amusement as he watched his friend putting away the array of sex toys back into the box. He would ask later which one Stanley used on Senku, and perhaps finally get the bigger details. But, for now, he let the idea be put away into the box as well. 

Closing the laptop, Xeno bid his friend a goodnight, getting a hum in return. Just as before, Xeno gave a small knock to the door before heading in, though paid no real mind to Senku as he walked to the room's dresser, beginning to undo the knot of his tie as well as the collar. "It may be a bit early, for someone as young as you," he paused for a moment, seeming to hold back his amusement, before continuing, "well, with a  _ mind  _ as young as yours, it may not be too late, but for me it is time for bed."

Senku had picked off about a third of the dinner by the time Xeno had come back into the room, though whether it was because of the flavor or lack of appetite he didn't know.

"Right, see you in the morning then." He mumbled, standing up and balancing all his items in his arms to bring them out. He didn't want to have to make two trips and walk in on Xeno in any state of undress.

Senku was quick in setting up his "bed" for the night, layering down towels then blankets in the bathtub, and arranging pillows around the back of it. It certainly wouldn't be comfortable, but it would work for sleeping. Some part of him wanted to go out to the couch until he was ready to sleep, but he'd rather not be around Stanley when Xeno was in the other room. At least not until both of them were asleep.

Glancing to the door, Xeno watched Senku leave with a small smirk curling at his lips. If Senku could make it through the entire night sleeping in the small bathtub then Xeno would applaud him, welcoming him to sleep in the same area tomorrow night as well. Though, there would be a good chance the boy would realize, with a sore body, that the bathtub was no place to sleep. Even  _ if  _ he was smaller, now.

Xeno undressed, putting himself into his sleep wear before turning to his bed. Senku had not left it too tidy, the plate of food still sitting on the blankets, those very blankets a total mess. Xeno removed the food, setting it on the dresser, before fixing the sheets of his bed. Once satisfactory, Xeno climbed into bed, a soft sigh leaving him as he laid himself down. Usually he would read before bed, but the day had been exhausting. He knew for Senku it was even more exhausting, a fact that would give Senku a fighting chance in being able to fall asleep in such an uncomfortable space. 

Turning off the side table light, Xeno let out a soft chuckle as he laid himself down. Maybe Senku wouldn't even make it through the night. He fell asleep with the thought of Senku's small frame trying to crawl into the bed next to him without making a sound.

* * *

It didn't take long for Senku to notice just how uncomfortable his makeshift bed was, though it took until around two in the morning for him to finally succumb to the pain growing in his back. He had been distracting himself by texting Taiju, but he'd really had an awful, exhausting day... and this "bed" wasn't going to let him sleep properly. 

As much as he hated to do it, Senku got out of the bath, before grabbing his pillow and blanket, and carrying them to Xeno's bed. He didn't want to sleep under the sheets with his mentor, if he absolutely had to be in the same bed.

The slight sway in the bed was enough to wake Xeno, though aside from his breathing pattern slightly changing, Xeno made no other signs to show that he was awake. He felt no real tug or pull on the blankets around him, which most likely meant that Senku was sleeping above the covers. Of course, Xeno could not blame him, not after his long day. 

And, of course, Xeno could turn his body. Wrap his arms slowly around Senku's waist and pull him close, whisper into his ear how Xeno knew Senku would not last long trying to sleep against the hard porcelain. Touch him, so softly in comparison to the wounds that Stanley had caused on his skin and in his mind. 

But, instead, Xeno knew he needed to wait. The wounds were still too fresh, after all. So, with a deep and content sigh, Xeno willed himself away from those thoughts, and back to sleep.

* * *

It was even harder for Xeno to will himself away from the desire to kiss Senku awake. He slept so soundly, his sneer gone and replaced with a soft mouth, lips just barely parted. Xeno did his  _ absolute  _ best. He was proud of his control. Though, he did sneak a touch, sliding Senku's hair from his face, thumb sliding across the round cheeks. They were cute - but they looked even cuter when the boy was pouting. 

After dressing, Xeno exited the bedroom to find a mess of bags near the entryway and kitchen. Blinking slowly, Xeno turned to Stanley, who sat at the couch, dressing himself in attire that could only suggest he had somewhere very important to be.

"You went shopping?" 

"You said you hadn't done groceries. Picked up a few things." Stanley was pressing his boot against the coffee table as he tied his shoes, an act that caused Xeno's eyes to narrow darkly. He'd have to clean there, later. No telling where those boots have been. 

Xeno pulled open one of the bags that sat up on the dining room table, an eyebrow arching as he noticed the rather large case of beer. "You picked up more than just groceries, I see. When will you be back?" 

A sigh came from Stanley, loud and gravely, "dinner time? After that? They always take up every damn second of our time."

"You'd think the military would be more prompt with time."

" _ You'd think. _ " Stanley repeated, now working on lacing and tying his second boot. "Oh well, bet your little brat is going to be excited for me to be gone all day."

Senku had woken up when Xeno was already out of bed, so surely he'd have some form of cockiness from the doctor, but he supposed it didn't matter. The bathtub hurt his back, and he did try to sleep in it, joining Xeno in the bed was only a last resort. 

He entered the kitchen as Stanley was preparing to leave, glancing over at each of the two men, before heading straight to the coffee pot and bread box.

"Speak of the devil," Stanley had finally finished, getting up from the couch, and grabbing his nearby coat, checking in a mirror to ensure he looked all right enough. The military outfit for these sorts of meetings were always a pain to make look just perfect. Once convinced he looked nice, the black uniform fitted perfectly to his frame, he made his way into the kitchen to fetch a bottle of water from the fridge.

"Feel free to do up dinner without me, in case this draws out longer than it should." He walked right past Senku then, making sure to lean over a bit as he locked eyes with the boy, not a single bit of shame or regret in the smirk he made. "You seem to be walking just fine, this morning." His grin grew as he tore his gaze away from Senku's glare, making his way to the door as he threw a wave back at the both of them, "see ya later, probably." 

Senku ignored Stanley's comments as he made his way around the kitchen, only looking up when his bread was in the toaster. Anyone that was looking closely would notice Senku's jittery movements, a far cry from his usual steady hands and confident walk. He doubted Stanley was the observant type though.

Once the door closed, Xeno gave a soft sigh, "he acts this way with everyone, don't take it the wrong way." He resumed putting away the groceries that Stanley had got, soon getting to the large case of beer. "Really, this is too much for one person..."

"What, the beer, or this whole situation?" Senku quirked an eyebrow, taking a slow sip from his coffee. "Though I guess both can be true, I'm assuming you're talking about the beer." Byakuya was never the type to drink that often, but Senku knew the standard was six per case, so this really  _ was  _ a lot if Stanley was only staying for another day or two. "He probably isn't intending it to be for just one person."

Xeno knew he shouldn't smile at Senku's cross statement about the situation being just too much for one person, but the boy's snark had always been amusing to Xeno. He was right, of course. Senku was going through a lot of mental and physical stress for someone so young.

"Well," Xeno began, looking at the large case again. "I suppose, technically, you are old enough to know the responsibilities of drinking, so I will not stop you if you wish to drink. I'm not too much on it myself." He walked to the dining room table then, placing the small black laptop beneath his arm, "feel free to do what you want - I'll be working in my office for most of the day." He began to turn from Senku, but stopped, turning his head to show a smile, "of course if you wish to still assist me as before, my office door will be open. I do have two desks, you can use one of them. I know you still like to know what's going on behind the scenes at NASA."

Senku nodded at the suggestion, taking a sip from his coffee mug, careful not to spill with his shaky hands. "I might, I'll have to see what kind of coursework I have going on though." He already knew he had some discussion posts to reply to, and a quiz to take, but surely those wouldn't take too long at all.

He did have to admit, he almost loved working alongside Dr. Xeno. It was often the highlight of his week, getting to assist a real NASA scientist, being one step closer to his childhood dream. It was a battle of his own ideals though. Was his desire worth it, worth working with someone that had directly and indirectly brought Senku so much hurt?

He quickly distracted himself by buttering his toast, taking his breakfast to the table to munch on it and finish the work that was so rudely interrupted by Stanley the day prior. He didn't bother to change from his pajamas, there was no point, and he wanted to be comfortable.

"Take your time, there is no rush," Xeno spoke as he walked off towards his office, the door having to be unlocked before entering. Xeno was not keeping anything from Senku, not really, but there were such things the boy did not need access to. Like the two brown bottles that sat high on a nearby shelf. Xeno glanced at them for a moment before sitting at his main desk. What a wonderful change the serum had brought to his life. Senku didn't feel the same way. But that would change. Eventually. 

A large portion of Xeno's work was the same now as it was at the NASA center, though working remotely had many disadvantages. But, it allowed him to stay closer to Senku, and spend free time on both Senku himself, as well as the serum itself. Such extreme changes. First gender, then body age. Of course, to make one regress age... that may be even more useful than the change of biological sex. Yes... more research needed to be done. But first, Xeno spent the many early hours of his day working through emails and other such things. 

By time the afternoon rolled around, Xeno left his office for a refill of coffee and perhaps something to eat. He passed by Senku who still sat at the dining room table. "You'll be excited to know that we're continuing further testing on the  _ Starship SN5 _ . The new blueprints and such for the engines came to my inbox this morning. I can share them with you, if you wish."

It took a lot for Senku to not act too excited. As much as he wanted to enthusiastically nod his head, exclaim that  _ yes, please share them, he'd love to see _ , he had to maintain some form of professionalism.

Instead he nodded, glancing up from his laptop. "Sounds interesting. You sure you won't get in trouble for that?"

Xeno blinked slowly, finishing pouring his coffee before sitting down at the dining table. "Senku, I think you have forgotten. Despite everything, you are still an intern with NASA, and you are still my assistant. You can view the blueprints as long as I have given you permission to view them, and I have." Xeno let a small smile grow, wanting to reach out and touch Senku's hand, but knowing that, right now, it would only result in the boy jerking back his arm. Instead, Xeno laid his chin into his palm, staring sweetly at Senku. "I will not deny, Senku, the things I...  _ desire  _ when it comes to you. But that does not mean I wish to take away the things you enjoy."

Senku blushed a little and nodded again, "Right. Well, it'll at least be nice to see the craft, since I'm sure it differs from the examples in my engineering class." He reached to the bowl in the center of the table and grabbed an apple. Xeno emerging from his office reminded him that time had indeed passed, and he would likely have to eat eventually. 

"What are the tasks I have, by the way?"

Xeno's smile widened, giving a small nod before standing, "If you care to assist me, then your tasks are about the same as any other day at the offices, though I suppose with a lot less lab work. Right now it is mostly corresponding to emails and looking over this engine," an arched eyebrow was sent to Senku, "I am sure you'd love to take a peek at it and see if you notice anything worth mentioning." He turned then, coffee in hand, heading back to the office. "It's your choice, after all, it'll be a long day of paperwork in the end."

"Sounds good. I'm almost done with this, so I'll join you in a little while."

Xeno soon sat back at his desk, placing his coffee onto the table. He had an extra chair in the room, though it didn't swivel or turn, but it would be enough if Senku really did come in and take interest in working again. He knew full well that the sneak peek at the new engine alone was enticing.

Indeed, after about an hour Senku had finished with the remainder of his work. He got up, poured himself a cup of coffee, then made his way to Xeno's office. Whether it was locked or not he didn't know, so he gave a soft knock on it anyway.

Xeno stood from his chair at the sound of the knock, opening the door and welcoming the boy inside, "no need to knock while I'm working," Xeno said with a soft chuckle, "you are my assistant, after all." He directed Senku to sit at the second desk. It was not as fully set up as Xeno's main desk, but it would do just fine for now. "I've already sent you the proper emails," Xeno went on then, nearly feeling back to 'normal', listing off the usual sorts of tasks he would give Senku each morning. At least,  _ almost  _ normal. Everything became all too real when he would glance over and see his assistant, cuter than ever and wearing pajamas at his desk.

Senku found himself pleased with the return to routine, happily responding to emails and transferring information into various documents. It felt nice to feel somewhat normal again, even if he had to go out and get a pillow to sit on, and his hands weren't as dextrous when it came to typing.

Later in the day, a sudden thought came to Xeno. His eyes fell to a small USB drive that sat on his desk. It held a very interesting video. With a curl to his smirk, Xeno grabbed the drive, standing and placing it in front of Senku's laptop. "For your viewing pleasure, if you wish. It's very interesting to watch.  _ Your transformation _ , that is." Xeno then gave a shrug as he sat, "you do not have to view it, but if you ever find yourself curious, feel free."

Senku stared darkly down at the USB that Xeno pushed towards him, before tearing his gaze away and looking back to his computer. "I'd... rather not."

A quick shrug came from Xeno, "that's your choice, I am not going to force you to watch it. Perhaps someday in the future." Xeno went back to his own work then, fingers quickly typing away, "or, if we are able to someday mass produce a rejuvenating drug such as this, I am sure you will see the effects on a different subject." 

Xeno let it drop there, however, noting Senku's discomfort with it. Instead, he continued with the long day of work, made a little bit longer now that he needed to work from home. 

It was nearing five when Xeno finally stood, arms stretching high as a sigh left him. "That'll do, for today. You can finish up whatever you are working on, I'll get started on dinner." He walked from the office then, being sure to bring his coffee cup with him, already a small idea in his head of what he would make for dinner. Perhaps a salmon dish, seeing as Stanley picked some up.

Xeno went to work, preparing for the dinner, eventually finding himself focusing once more on the beer in the fridge. A small smile formed on his lips thinking back to the night not too long ago, his adorable little assistant at the launch celebration, just a little too young to be legally drinking. Senku was,  _ legally _ , not old enough to drink. In body, he was far from it. But his mind was mature enough, Xeno knew that. And some alcohol may cause the boy to finally relax and let his guard down properly. 

It all just depended on if Senku would drink in the first place.


	8. Experiment 08

Senku quickly shut down his computer and brought his own dishes out of the office, finding Xeno into the kitchen. He stopped for a moment to grab his Switch and set himself up at the table. "What's for dinner, then? It'll probably be better than last night's..."

Xeno gave a small laugh, "I am no chef, but I get by. Though, yes, I suspect it will be much better than last night. I am simply baking some salmon with a garlic butter. It will be ready soon," Xeno had already put the fish into the oven, now beginning to clean up the kitchen after the food preparation. He opened the fridge to return a few ingredients, eyes falling again on the beer. He hummed softly, considering... before leaning down to dig into the case, bringing out one for himself (one would be far from enough to affect him), and waving another at the boy, "Did you want any? It's been a long day... a long  _ few  _ days, actually."

"Sounds good." Senku turned back to his game for a moment, before noticing movement from the corner of his eye. He gave the can a discerning look, before sighing. "I guess I could have one, but... Byakuya's let me taste his before, and it was nasty." Despite his negative stance, Senku still took the can and looked it over.

Xeno sat at the table with his own beer,opening the can. "It's a required taste, I only partake in drinking beer every few months or so. Usually when Stanley visits, since he enjoys it." He took a slow sip, the bitter taste not sitting too pleasantly on his tongue, but he opened the bottle so he intended to finish it. He glanced to Senku then, giving a small smile to him still looking over the can. "Well? At least try it and see if you like it."

Senku sighed before setting the can down. "Can I just try yours? Then it's not wasted if I don't like it." There was some piece of him saying not to do it, that Xeno would probably get off on the indirect contact, but Senku didn't care at this point.

A small chuckle came from Xeno, reaching over to place his can down in front of Senku. "I don't mind at all." Xeno soon laced his fingers together, watching Senku with his chin propped against his hands. He would have to study his face. Watch to see if his face twisted with disapproval or not. Either way, his reaction would be adorable. Xeno already knew that.

Senku picked up the can and inspected it for a moment, before taking a tentative sip. Nearly immediately, his eyes narrowed and his lips pressed together tightly as he handed the can back to Xeno, shaking his head.

Xeno was expecting the reaction - but actually seeing Senku's face contort so fast, and the way he desperately shook his head, it caused a louder laugh to leave Xeno. His little assistant really was the cutest thing. He took the beer back, placing it on the table in front of him. "All right. So you're not a beer type, noted." A small hum left Xeno as he pulled out his phone, pulling up Stanley's name. Stanley so rudely asked Xeno to go to the store to pick up something last night. So his friend should be willing to do the same. "How about... something a little stronger? And also, easier to mask." In the message screen, Xeno gave his friend two items to pick up. Soda. And some vodka.

"I guess...? Not too sure about the 'stronger' part, though." Senku got up and fixed himself a glass of water, sipping it to get the fermented taste from his mouth. "I do have some coursework to do in the morning, y'know. I'd rather not have a splitting headache for that."

Xeno hummed softly in response, "there are a few ways to prevent a hangover. Staying hydrated will help a lot, but we need only assure that you don't drink too much in the first place." A happy median would do quite nicely, if Senku was willing. Relaxed enough to weaken his barriers. But not so far gone that he couldn't walk on his own. 

Xeno already had experience with that. It may have been fun, but it had no real merit other than being a great way to see some wonderful expressions on Senku's face. 

* * *

Stanley was right when he said that he would be getting home well past dinner. The salmon had already been cooked, ready, and eaten on by the time he came through the door, a few grocery bags in tow. Xeno looked over from the kitchen, cleaning up and putting away most of the leftovers, though a prepared plate still stayed out for Stanley. "Hope you didn't mind, we didn't wait for you."

Stanley only gave an exhausted laugh as he brought the bags to the table. "I figured I'd be late, but god I'm starving anyway." He went to the plate, not even caring that it was cold as he held it in his hands, leaning against the wall as he picked at it. "Wasn't exactly sure what you wanted me to buy, so I just got a few things."

Xeno let out an inquisitive hum as he dug through the bags, pulling out a few different jugs of soda as well as the large glass bottle of vodka. The size of it made Xeno chuckle a bit - it was big, way too big for three people and one evening. There would definitely be left overs. "This will do just fine, thank you," Xeno said, moving to the cupboards to grab a few glasses. He would go for simple coke and vodka for now. If Senku wanted to try other flavors, well... 

Perhaps one drink would be enough. Two shots - not enough to bring down a grown man, but Senku's metabolism most likely matched the age of his body. His tolerance would be next to nothing. Xeno would watch him closely, and determine if he needed more, but he had a feeling this would be plenty. 

Xeno was about to mix the drink in the kitchen, but he had become all too aware of Senku's distrustful mind. So, instead, he brought the items out into the living room where Senku sat, busied by his game. He sat beside the boy, placing the items out onto the coffee table.

"Coke," Xeno said, pouring that first, "vodka," now second, the two shots worth. Once mixed, he handed the glass to Senku, his usual kind smile showing, "perhaps this will be more to your tasting."

Senku watched carefully as Xeno poured the drink, taking note that both the bottles were sealed before coming into the living room, and the cup had no pills or other offending items at the bottom. He nodded, still a little unsure, and took the cup from Xeno. The taste was nowhere near as offensive as the beer, though there was still a slight alcoholic tinge under all the sweetness. He could work with it though. "Thanks..."

Xeno nodded warmly, taking the bottles now and returning them to the kitchen. He knew that Stanley would be wanting to drink some, so he left the bottles on the kitchen counter. Xeno had no real plans on drinking himself, but he still poured some soda for himself. A nice change from the constant coffee - and it wasn't as if the drink was void of caffeine.

He held a casual conversation with Stanley as his friend ate. Perhaps too casual, considering the past few days. Stanley's recent days in the army, Xeno talking about the launch. Nothing was strange. Nothing at all. 

Once Stanley had finished his meal, Xeno slowly walked back out into the living room. He took the spot near Senku on the couch, finding the television remote. "Perhaps a movie?" He questioned, though he was already searching through screens to find one. Stanley followed into the room as well, though he took a seat in the armchair, feet propped up on a nearby foot rest, a drink in his hand that looked more like vodka and coke than coke and vodka. 

It took a bit to find a movie that interested them all, eventually deciding on a space exploration movie that was also packed full of action. As the movie began, Xeno leaned towards Senku, whispering in a hushed voice, "if you pop off with facts during the movie, about space or how something is wrong, it really pisses Stanley off." The smile Xeno gave was encouraging Senku to do just that.

"Good to know," Senku whispered back, taking a slow sip of his drink. He had nearly finished it in the time that the two older men were talking, and he could already feel a warmth in his face. Probably best not to drink any more, maybe he'd go get just a plain soda when they reached a lull in the movie. 

The movie was decent enough, obviously not trying to be a documentary, but Senku still took enjoyment in commenting on the various inaccuracies and tidbits of what he'd learned in his various astronomy classes, and watching as it became harder for Stanley not to snap.

With every passing comment during the movie, it was obvious Stanley was growing in irritation. It wasn't so much the facts, it was just that the two of them were so fucking good at piping up with their damn comments when an important action scene was going on, or when someone on screen was talking. When it wasn't Senku popping up to mention how zero-gravity totally didn't work like that, it was Xeno mentioning how dangerous it was to have unchecked floating liquids in the meal rooms. 

"It's horrible for the air recycling system," Xeno was adding, "a single crumb can cause an entire cascade of issues, this is why food preparation is its own entire science--"

"Oh my  _ God _ , will you both please _ shut up _ ," Stanley began to gesture at the screen, "they are about to be killed off by aliens, do you really think they care about the air systems?!" 

"Well-" Xeno had begun, but Stanley gave his friend a dark look that threatened to throw something at the couch the next time they spoke. Xeno couldn't help but snicker, quite proud of the both of them. 

Stanley scoffed as he looked back to the screen, "you two really are a match made in heaven, huh?"

Senku rolled his eyes at Stanley's outburst, though a cocky smile made its way onto his lips. "Sure, whatever." He glanced down at his empty cup, and went over his options. He could ask Stanley to get him a soda, but he still didn't have much trust in the man. He could ask Xeno, but then he'd have to be alone with Stanley. And he could go get it himself, but he had just gotten comfy....

Finally, he made up his mind, and nudged Xeno with the cup. "Could you go get me a refill? No alcohol this time."

Xeno gave a quick smile to the boy, taking the glass slowly, being sure to let their fingers graze each other as he did so, "of course. Sit tight, I was thinking of getting some more myself." Xeno stood then, grabbing his own nearly-gone glass of soda, walking his way into the kitchen. 

Senku asked for no alcohol. It was probably best for him to stop. Two shots in a body that young was already bringing him into a much more relaxed state, but one more would not hurt. Senku could not see the kitchen counter from where he sat. And his mind was focused on the movie and already fuzzy. He would not notice one shot this time. It would be much less strong than before, and any taste he was sure the boy would blame on a residual taste left in his mouth. 

Xeno made his way back, handing the boy the glass of soda, sitting back next to him with a glass of water himself. "Ah," he directed his attention back to the movie, "so they intend to do a spacewalk?"

"Yes," Stanley's voice was firm, "don't talk through it, I wanna see if this guy dies or not."

Senku stayed obediently quiet, watching the movie idly, and managing to keep quiet on the inaccuracies  _ ("the alien wouldn't make any noise when out in space") _ as he sipped on his soda. He still had an aftertaste of alcohol, but it was probably just a remnant of his previous drink, so he didn't bother to mention it.

As the movie went on, the room got quiet. It was preferable, for Stan, who enjoyed the quiet room while the movie played on. But Xeno made quick note of Senku's sudden silence, no longer giving his snarky quips towards the screen. Perhaps Stanley's outburst actually scared him, or at least intimidated him enough into silence. 

Xeno leaned over slightly, his hand resting on Senku's knee as he looked at him, "are you feeling okay? Not too much of the alcohol, I hope." He glanced his way back to Stanley, who didn't seem to take notice of their whispers. Very slightly, his grip on the boy's leg tightened. "Don't take him too seriously. He complains, but I think he secretly loves it."

"I'd hope it's not the alcohol, I... I've only had two shots." Senku rubbed his eyes, surprisingly not jerking away from Xeno's touch. "I'm jus'... tired..." He shook his head, then placed his once again empty cup on the coffee table before leaning on the arm of the couch as his eyes half-closed.

Xeno gave a small hum... perhaps three shots was too much, sending Senku right into the sleepier stages of drunkenness. Though, the fact that Senku did not seem to notice, or at least mind, Xeno's touch to his knee was giving Xeno the urge to be a bit more...  _ bold _ . Stanley was still focused in the movie, completely unaware of it all; Xeno's hand slowly rising, now softly gripping at the boy's inner thigh.

"Your body's tolerance simply does not match your mind," Xeno said, feigning concern, "perhaps two was too much. Do you need me to carry you to bed?"

Senku thought for a moment, almost getting up on his own, before rolling over and nodding, holding his arms out. "Yeah, I... I guess." He wanted to keep watching the movie, but he was finding himself yawning and letting his eyes close.

The outstretched arms asking to be held, the small yawn... It took everything for Xeno to not push him into the couch there. It would be so easy. Senku seemed so compliant. But Xeno needed to play along, just for a while longer. So he slowly wrapped his arms around the boy, pulling him right into his lap, body moving as if he was about to get up... but stopping, laying his back against the back cushions of the couch, nodding to the screen, "let me watch this part first, all right?"

His hands laid on Senku's waist, the boy straddling him. Would Senku even notice? The way Xeno's hands slowly slid down his hips, daring to grip softly, wishing he could tear the clothes from him then and there.

Senku groaned, bonking his head against Xeno's cheek. "You're so mean..."

Despite his apparent upset, Senku was... surprisingly comfortable. He was surrounded by warmth, his own chest pressed into Xeno's, if he were more present he would have noticed the hard-on the older man was sporting. Once the music seemed to change, he started to move again, patting at Xeno's chest. "Okay, bed now. You can... can come back."

"Nonsense", Xeno purred out, the hands on the boy's thighs beginning to grip tighter to keep him in place. He still spoke softly, not enough to alert Stanley over the loud action scenes. "This is nearing the...  _ climax  _ of the movie, I don't want to miss out on what happens." It was then that Xeno dared to move things a little further, his face slowly moving to the crook of Senku's neck, his lips placing a small chaste kiss along his warm skin. "You can rest here if you wish, until the end of the movie."

Senku whined again, letting his face fall into Xeno's shoulder. "But I wan' a blanket... 'n you're not comfy." He leaned back just enough to give an angry pout, before falling forward again. "Too pokey..."

A low chuckle now left Xeno. He was...  _ so cute. _ Of course he was. His assistant was always the epitome of the word, even his ornery complaints were adorable. Two shots - definitely enough to calm the boy... but it took three to make him  _ whine _ . Xeno's hands begun to drag Senku's hips closer to his own, the growing erection in his pants pressing into Senku's still clothed sex. "Is that so," Xeno whispered out, voice sugared and sweet, attempting to coax Senku's desire, "what exactly about me is  _ 'pokey' _ , hmm?"

"All your joints, 'n pokey bones." Senku poked at Xeno's cheek, still not quite noticing the pressure in his groin. It did feel nice, and warm, but all he could do was puff up his cheeks and continue to glare.

A content hum left Xeno, eyes closing. If only Senku could act like this all the time, near childish in a way. Would he act similar if full grown? Even then, the behavior would have caused more arousal to swirl in Xeno's groin. Xeno slowly tilted his head, softly kissing the finger that was once poking at him. "Perhaps, then, I can treat you softly?"

Xeno had dreamed about kissing Senku. All the different ways he could do it. In public. At work. In his bed, his body writhing with pleasure. He never imagined he would desire to kiss Senku while he was under the influence, but the chance was right in front of him, presenting itself so perfectly. 

So Xeno leaned forward, his lips laying against Senku's, the kiss sweet and chaste as he waited, testing the boy's reaction.

Senku tensed a little at the kiss, a slight sugary taste lingering on Xeno's lips. He didn't want to pull away though, it almost felt...  _ nice _ . He tried to think back to his practice sessions with Taiju, he would've been about this small, but his memories evaded him. Instead, he just closed his eyes and relaxed in Xeno's hold.

Perfect...  _ perfect _ . Xeno did well to control his breathing, the act of Senku relaxing in his touch enough to entice a heavy breath to leave him. His hands moved so slowly, as if a sudden movement would spook Senku and cause him to pull away or yell out for him to stop. They took Senku's jawline, fingers sinking into the boy's hair as his thumbs rested on his cheeks. Xeno began to take Senku's bottom lip between his own then, suckling gently, waiting until the moment that Senku's jaw began to open to let his tongue sink between his teeth.

Senku let out a whimper as Xeno bit and probed into his mouth, though it was inaudible over the music and sound effects in the background. His hands curled in Xeno's shirt, though he couldn't reciprocate very well, his head still swimming wildly.

A shuddering moan left Xeno, filling Senku's mouth. His little whimpers were becoming enough to drive him wild, and all they were doing was sharing a kiss. Xeno began to rock his hips, causing Senku to fall even more into his groin, grinding into his erection - an action that made Xeno pull back from the kiss, biting his lip. The moan that threatened to come out would have alerted Stanley...

"Senku..." His voice was so low - too low for even Senku to hear, perhaps. He couldn't stop with just kissing, one of his hands now sliding down the boy's chest, "let me touch you." He didn't fully wait for permission, his hand now sinking beneath Senku's shirt, running his hand slowly across the warm skin. He was so small, Xeno could cover nearly half of his torso with his hand alone. The hand slowly raised, a soft kiss once again taking Senku's lips, Xeno's thumb pad flicking against a nipple.

Senku let out another whine, a little louder this time at the intimate touches. It was warm, so warm. So comforting, each touch was feather light and made his head feel like it was floating, or maybe that was just the alcohol. He wanted to look back, see if Stanley was watching, but he didn't know why, it would only draw away the warmth.

As soon as the whine left Senku's mouth, Xeno's eyes shot open, looking straight at Stanley. His friend still sat, drinking slowly at his drink as he watched the movie. It helped that the scene was high in action, a lot of yelling and music. Xeno sure heard that sound, though, the moan like a bolt of electricity running through him. Not only was Senku not saying  _ no _ , he was responding so beautifully... 

And he needed more.

Xeno kept his fingers teasing Senku's nipple, but his other went down further, slipping so easily beneath Senku's pajama bottoms. He didn't dare go beneath his underwear, yet. Instead, Xeno ran his fingers across Senku's slit with the pads of his fingers, making sure to continue the kiss to perhaps distract Senku's mind from retreating.

Senku's lip trembled ever so slightly as his hips began to move on their own, rutting against the gentle fingers. Each movement sent electricity through his veins, and his eyes slowly closed while his mouth drifted open. He let out quiet pants into Xeno's chest, his fists clenching in the man's shirt.

This was it - probably the most responsive reactions Senku had ever given since that day in the labs, when Xeno was able to mask everything as a scientific endeavor. Xeno used Senku's open panting mouth as permission to continue invading the boy's mouth with his tongue, running along his cheeks, his teeth, every inch he could get to. The hand from Senku's chest moved to the back of his head, keeping it stable as the kiss deepened, his other pulling away from Senku's groin only to then slip beneath his underwear. Xeno's fingers delved right between Senku's folds, sliding against his clit, Xeno soon massaging his finger pads against the swelling mound. 

"See- I fucking told you!" Stanley's loud voice boomed from the other side of the living room, Xeno's eyes snapping open to look over, but not stopping his kiss nor his touches on Senku's body. "I knew the chick would be the only one left alive, it's always the chick." He began to turn his head to look at them, an action now that caused Xeno's hands to still in anticipation, "I bet you that she--" 

Stanley's words stopped, finally fully looking back, his eyes wide for just a moment before soon letting out an exhausted groan, "you're fucking  _ kidding  _ me - during the movie?! I'm  _ right here. _ " 

Xeno pulled from the kiss then, a grin growing at his lips as he moved to Senku's ear, whispering low, "don't listen to him, Senku. Remember? He can't touch you, anymore... he's only jealous."

Senku pouted, crossing his arms and sending back a glare at Stanley, before hiding his face in Xeno's chest once more. "C-can we  _ pleeease  _ go to bed? I'm tired..." He whined, though he tilted his hips towards Xeno's hand once more.

As Senku began to cuddle into Xeno's chest, Xeno allowed himself to nuzzle into the boy's scalp, enjoying just the scent of him. "You're not tired," Xeno hummed out, his voice gentle and his hand rocking against Senku's clit even more. Despite Senku's desire to leave, his body was reacting, Xeno's fingers having more ease in teasing the sensitive mound with the wetness collecting on them. "The alcohol is simply binding to a few neurotransmitters - making you feel overly relaxed." 

Xeno ignored the annoyed sigh that came from Stanley, watching with an arched eyebrow as he stood from the armchair and grabbed the television remote from the coffee table, pressing at it to pause the movie. "I'm taking a piss," he said, his voice obviously irritated, though Xeno knew he wasn't  _ truly  _ upset. 

Once Stanley walked past them, disappearing into the bathroom, Xeno moved to tilt Senku's chin, smiling warmly. "Do you want to play a game with me, Senku? It's called  _ 'tease Stanley, and get back at him for yesterday _ '. You only need to be willing."

"I... okay..." Senku nodded, his eyes half-lidded. "What are the rules?" His head laid heavy in Xeno's hand, happy for the rest. "It can't be a game without rules." His voice was quiet, though his hips never stopped twitching.

Xeno's smile warmed, though he couldn't help the lick he did to his lips. His own cock was throbbing at this point, desperate to be released, but he'd ignore the need for now. It would make the act later on feel so much better. 

"You're  _ right, _ " he purred out, his forehead now pressing against the boy's. "The rules are simple. Your pants need to be gone - I can help you with that. You can't let Stanley touch you, no matter how much he begs, or how much you may want it. And.. " Xeno pecked his lips, so softly, "you need to let daddy do as he pleases-" 

The last comment caused Xeno to pause. In fact, he gulped hard. Sure, the thought had stirred in his mind before. Senku so small, the way he whined, the mental image of him moaning out the name... but just  _ suggesting  _ it was overwhelming... 

"In fact," he continued, voice huskier than before, running his thumb across Senku's bottom lip as his other hand delved deeper between Senku's folds, never entering him but slowly teasing around his entrance, "if you wish for me to answer you... you must refer to me as 'daddy'. Is that understood?"

Senku looked up curiously, his brows furrowed together. "Daddy...?" It must be an American thing, surely. It wasn't common for Japanese pornos to delve to nicknames like that, but... it didn't feel wrong, or strange. At least not now. "O-okay... daddy..."

Xeno gulped once more, his eyes fluttering closed. He could hear that Senku felt nervous about using the word, he could feel his uncertainty, but that only made it better. "What a  _ good boy _ you are," Xeno let out, quickly overtaking Senku's lips with his own once more. He needed to drink him in, to completely devour him.

He broke the kiss for just a moment, his hand now finally leaving Senku's sex to tug at his pajama pants, "we need these off," he whispered into Senku's mouth, "move your hips with me." Xeno did his best to guide Senku's hips, raising them higher as he tugged them down. He needed to maneuver the boy's legs to slide them off entirely, but it not take long before Xeno was able to drop both the pants and Senku's underwear to the side.

Before Xeno could properly bring his hand back to Senku's groin, he felt the back of the couch compress behind him, head slowly glancing upwards to see Stanley standing above the both of them, leaning over onto the back cushions. 

"You're going to do this here?" He asked, eyes leaving Xeno to look at Senku, eyes traveling down the boy's body, and soon looking towards the discarded clothing on the couch. "I sleep here, you know."

But Xeno only chuckled, looking away from Stanley as he nuzzled at Senku's neck, "see that? He's already so jealous."

Senku stared up at Stanley, eyes wide and glassy, but his brows knit together in a pouty glare. He wrapped his arms tightly around Stanley's shoulders, before he quickly hid his face again. "I-I don't... I don't know i-if I like bein' watched..." He mumbled, just loud enough for Xeno to hear.

"Is that so?" Xeno's hands slowly wandered down Senku's hips, nails grazing at the skin of his ass and thighs. "How do you know, if you've never tried before?" 

A scoff sounded out above them, Stanley walking more into the living room. But he didn't come near them, instead walking to the sliding door that led to the outside balcony. "I need a smoke," he let out, sliding open both the curtain as well as the door itself, letting in a sudden chill with the night air. As he walked out, he dug into his pockets to fetch his cigarettes and lighter, turning to then lean his back against the balcony as lit the cigarette that was held in his mouth. Breathing deep, he peered back into the living room, arms crossed, eyes not leaving the two of them. 

Xeno was not able to prevent the smirk that grew on his lips. If Stanley was truly upset, he would have just left the apartment to go on a walk, or find another way to distract himself. But no - the two of them shared a single glance of full understanding. This would be fun. 

Xeno softly nuzzled once more at Senku's neck, moving up to whisper into his ear, "his eyes are all over you, even from outside," One of Xeno's hands stayed on Senku's ass, gripping as he tugged slightly, spreading Senku to show more of his warm sex. His other hand slipped down between his legs, two fingers capturing Senku's clit between them, pinching and massaging at a speed much quicker than before. "I'm sure you look amazing from his view..."

Senku jerked his hips against Xeno's hand, soft whimpers and shy moans leaving his parted lips. Even with his eyes half-lidded, he couldn't seem to tear his eyes away from Stanley. He was clearly watching, was he really jealous like Xeno said? Would he break his promise? Hopefully not, he wanted to keep himself from Stanley's reach, not wanting those rough hands on his skin anymore.

Xeno glanced again to his friend, the only light illuminating Stanley's face on the dark balcony being the cherry of his cigarette. It was easy enough to see his stare, though, deep eyebrows focused on Senku's squirming body. Xeno allowed his fingers to sink deeper, past Senku's clit and deep into his folds, his two middle fingers now playing at his entrance. He softly hummed to the boy, an attempt to sooth him as those very fingers delved deep, aided by the juices dripping eagerly from Senku's body. He wasted no time in slipping them right back out, delving once more, soon starting a rhythm as his fingers attempted to curl each time.

Senku let out soft pants and his tongue poked out of his mouth, his eyes finally closing. As long as he couldn't see Stanley, he wasn't being watched, right? Even still, the lingering cigarette smell brought him back to the day prior, and he squeezed his eyes shut tighter, and his whines became slightly more upset.

"Shhh, shh..." Xeno softly began to shush the boy, free hand rubbing up his back, "you're just fine, aren't you? It's only me and you, you have control over your arms and legs." Small kisses were soon placed along Senku's forehead, Xeno's lips smiling against Senku's flushed skin, "feel the power of it, Senku. His eyes may be on you, but there's nothing he can do about that. You can tell him exactly how you feel." Those kisses continued down Senku's face, Xeno's hand now coming around to prop the boy's chin up, forcing Senku to look at Xeno directly, "I could fuck you - right here, right in front of him." His face slowly moved closer, licking now at Senku's bottom lip, "you agreed to let me do as I pleased, remember?"

Senku stared into Xeno's eyes, slight tears forming at the intensity. He gripped tightly at his shirt, grounding himself with the soft fabric, before he quickly tucked his face away into Xeno's shoulder. "I... y-yeah, I... I did... daddy..."

" _ Good... _ " A shiver ran down Xeno's back, the throbbing in his pants entirely unbearable now. "I'll need you to move, just a bit," Xeno coaxed Senku's hips back, hands quickly undoing his pants, a shudder of relief felt through his body as he finally released his cock. It stood high, already pressing into Senku's belly, pre leaking onto his pajama shirt. "Come, like this..." Xeno said, voice barely audible, taking both Senku's hands and placing them on his cock. For just a moment, Xeno's eyes closed - his hands were so small.... "You know what to do, don't you...? I'm sure my sweet assistant is not innocent enough to have never touched himself."

Senku gulped, staring down at Xeno's length, his hands trembling slightly as he took gentle hold. He carefully spread the precum over his cock, before stroking with a light and unsure touch. Of course he had done this before, he had even done this to someone else before, but it felt so odd now...

"It's okay..." Xeno could feel the tremors in Senku's hands, his own covering his slightly, placing small kisses all along his jawline. "You're amazing, you're doing amazing." With his own hands, he caused Senku to start pumping faster, "you can tell, right? Smaller than Stanley, surely I won't hurt you at all."

Speaking of such a Devil, Xeno glanced up as he heard the balcony sliding door shut, the curtain soon closing with it. Stanley walked into the room slowly, eyes locked with Xeno - a stare that made even Xeno feel a sudden shiver of anticipation. He and Stanley shared most things. They were tightly knit friends, to the point that he could ask Stanley to help him force the young boy into submission. But they had never shared such an intimate moment as this - something about Stanley's stare suggesting that it would not end after tonight. He walked around to the back of the couch, leaning his elbows down against it, face near Xeno's as he looked to Senku's unsure expression. 

Stanley had opened his mouth to say something, but Xeno beat him to it, "you stink of nicotine. Please go wash your hands." He began to tickle at Senku's chin then, "Senku, tell Stanley he stinks."

Senku pouted, though his nose did wrinkle at the scent of cigarettes. He tried to keep his eyes off Stanley, focusing on continuing the movements of his hands.

"Ah ah," Xeno's hands stopped Senku's movements, his thumb and forefinger holding either side of the boy's cheeks, "I believe I told you to do something. Be a good boy, now. Tell Stanley how fowl he smells." 

Stanley was sighing before Senku could properly answer, pushing away from the couch, "I get it - it doesn't even smell that bad." He walked away from the both of them, entering the kitchen. Eventually the sound of running water could be heard. 

With a soft snicker, Xeno directed his attention back to Senku. "Does Stanley scare you? He's sort of a big bad wolf, isn't he?"

Senku nodded slowly at the question, his eyes glancing off to the side in embarrassment. "I-it's too soon..." He mumbled, his hands once again starting to shake in Xeno's hold. "I... I really w-wanna go to bed..."

"Are you sure?" Xeno's hands began to rub against Senku's. Even with the alcohol weakening his barriers, it seemed that Senku was still weary of Stanley. Xeno was hoping that it would have brought out a different side to him, one willing to flip Stanley off as he rode Xeno's cock. But, such things were far in the future, it seemed. 

But it was no matter - Xeno could fuck him here, and receive Stanley's dark glare, and most likely get a lot of choice words from his friend in the morning. Or, he could fuck Senku in his bed, where the boy would be more comfortable to let out his moans, hopefully loud enough that Stanley could hear, and he would still get choice words from Stanley the next day. 

Xeno laid a soft kiss on Senku's head, though the shaking grip on his cock caused his hips to slowly push into the hold, a sigh leaving him. "We can stay. We can teach Stanley a lesson together. Or, I can take you to bed. But the game will not end."

Senku pursed his lips, staring at nothing as he thought. "I... I guess I c-can stay out here..." He wanted to hide his face, but he couldn't bring himself to move his hands.

Xeno hummed proudly, giving one more kiss to Senku's forehead before running his lips down the side of Senku's face, more kisses laid in his wake. "You are such a good boy, did you know that?" His hands finally left Senku's alone, though his hips pushed up into the boy's grip one more time to encourage them to move more. Xeno's fingers slowly crept back between Senku's legs, one grabbing at his thin leg to keep him steady as the other slipped between his folds once more. "So good, in fact, I'll make sure to make you feel really good before I take you to bed." 

Stanley's steps could be heard nearing again - which was perfect timing. Xeno glanced up, catching the glare of his friend, Xeno returning the stare with a smirk of his own. "Stanley - think you can lend a hand? Or, well - I need some things from the box. And something else you seem to have left in my room." 

Stanley had stopped in his tracks, his eyes narrowing further before sighing deeply, walking completely out of the living room and towards Xeno's bedroom. He was gone for a short while - Xeno distracting the boy on his lap with gentle massages to his swollen clit - until Stanley finally reappeared near the couch. He dropped two things on the cushion near them; the bottle of lube as well as the package of condoms. 

"I have no idea why I'm helping you," he stated flatly, walking back to the chair he had sat in before, turning it away from the television as he sat, this time extending his legs to rest on the coffee table. 

Xeno only chuckled at the comment, "obviously you like to watch."

Senku whimpered quietly, bucking his hips against Xeno's fingers while waiting for Stanley to get back. He stared at the items that were so unceremoniously tossed on the couch, his swimming head full of conflicting thoughts. He wanted to lay down, he wanted to scream, to run, to open his legs and let it happen... Xeno said he wouldn't hurt him, right? It was okay to stay... even if Stanley was watching so intently.

Xeno's hand reached over, grabbing first at the condoms. He managed to dig into the box with the single hand, fishing out a single condom, even opening the wrapper with his teeth - all so that he didn't have to bring his fingers away from Senku's clit. He would need help, though. Xeno brought the condom down to Senku's hands, placing the rubber ring on the tip of his cock, nuzzling softly at Senku's temple. "You know how to put one of these on, I'm sure."

Senku pursed his lips and nodded, though his hands were still shaking as he rolled the silicone down Xeno's length. At least he cared enough to wear protection, he wasn't nearly as bad as Stanley, right?

A soft shudder left Xeno, eyes fluttering closed as he focused on the sensation of Senku's small fingers rolling the condom out over his shaft. His hand left Senku's warmth, only for both of his hands to grip at the boy's thighs, breathing deep as his cock twitched eagerly in Senku's grip. "There you are... that's perfect," he hummed out, wasting not a second of time as he reached over to the bottle of lube. He squeezed a generous amount onto his hand, coating his length, a moan mixing with a sigh as he gripped tight for just a moment. 

"Come, like this," Xeno began to direct Senku's hips, pulling and positioning him until his cock head laid right at Senku's entrance. "It's your choice - lower at your own pace. You control this part." It wasn't the full truth - Xeno could easily buck his hips up at any time, but it was important to let Senku feel that sense of control in the situation.

Senku held tightly to Xeno's arms as he lowered himself. It was agonizingly slow, causing him to shake and let out quiet whimpers. It was all too familiar, but at least it didn't hurt.

Xeno did his best to meet Senku's gentle shaking with small shushes, kissing gently at every bit of his face; cheek, jawline, lips, his nose. "You're doing great," he whispered out, hands rubbing softly at his hips, "only as much as you can take, there you go..." Xeno watched as their bodies slowly became closer and closer, Senku's entire body quaking by the time he had Xeno nearly fully sheathed. Senku's innermost walls were so hot, clenching around him as they adjusted to the slow invasion of his length. 

Curiosity of his friend had gotten the best of him - Xeno's gaze soon snapping over to look at Stanley. Their eyes met the second Xeno looked over, Stanley's stare causing another shiver to run through Xeno's body. Stanley was not doing anything - in fact, he seemed to be doing his best to look bored. But it was easy to pick up that the man was turned on. The way his legs were crossed, or how his half-lidded eyes glared at the two of them. Even the red tint to his friend's cheeks. 

Wearing a small smirk, Xeno turned his attention back to Senku, "at your own pace, now," he said, humming softly as he continued to rub soothingly at Senku's hips and back.

Once he had taken Xeno's full length, Senku leaned back against Xeno's chest, steadying his breath while he allowed himself to get used to the fullness. Something Stanley had neglected to do. Surely Xeno was being somewhat courteous to prove a point, but Senku didn't mind, not right now.

Xeno happily accepted Senku's body laying against him, his own arms embracing the boy even more. A hand slowly flowed up and down Senku's body, soon both of them taking either side of Senku's ass. A gentle pull of his cheeks - the view Stanley must have been receiving... A time in the future, Xeno may have to ask for a picture. Not digital, of course. He knew better. 

"His eyes are all over you," Xeno said softly, trying to entice Senku's hips to move, but leaving the full decision up to him. "He can see  _ all _ of you... how beautiful you are..."

Senku kept his eyes closed, not wanting to make accidental eye contact with Stanley. "I-I don't..." He trailed off, wanting to claim he didn't like it, but... didn't he? Shouldn't he like having someone that wronged him be forced to sit there with no satisfaction?

He let out a quiet sigh, before he adjusted his hips to achieve a more comfortable angle. He didn't want to move, not yet at least.

It was becoming unbearable... Xeno's hips softly jerked, shoving himself deeper, just a bit. His breath felt heavy, eyes closing. "Senku..." He whispered out, knowing it was the best idea for Senku to feel control in this, the quickest way to having him more eager to do these things in the future. But it would be so easy.... To just tug at his hips, raising him and throwing him back down onto his cock... 

But Xeno didn't. Instead, he continued to rub at Senku's body softly, intending to comfort him. "It feels...  _ amazing  _ inside of you," Xeno's voice was husky, whispering into the boy's ear, though his tone was loud enough for all in the room to hear, "you're so tight... perfect, as if you were made for me." Xeno began to kiss at Senku's temple now, his hips now rocking forward, causing friction between them, "it will feel even better once you move..."

Senku let out a whine at the sudden friction, his lips parting slightly. It was easily a much more pleasant feeling than the day before, but it was still alien to Senku. "I-I... I don't know if I... if I can..." It was true at least, his legs were still incredibly sore from his activities the day prior.

A sly smile slowly appeared on Xeno's lips. "I see... poor thing... allow me to help you, then." It wasn't really permission, but Xeno was intent on treating it as such. The grip on Senku's hips turned more harsh now, enough to tug the boy's hips upwards before gently bringing them back down. At least - as gently as Xeno could manage, his own hips rocking upwards once more. He repeated the action, continuously giving small hushes to Senku's soft whines. "How does it feel...? Tell me," Xeno said it before delivering one good thrust upwards, feeling Senku's walls clench in shock around him. "How good does it feel?"

Senku couldn't help the squeaks and whines that escaped his throat as Xeno fucked into him. Even though Xeno was noticeably smaller than Stanley, it still felt like Senku was being completely filled. "G-good... good..." he mumbled, hands gripping tightly to the fabric of the couch below him.

Xeno hummed contentedly. With Senku on top, it gave that semblance of control. Or, at least enough of it to now allow Xeno to keep Senku's hips mostly still, thrusting upwards once more - then again, again, each thrust bringing a new speed. Xeno's eyes soon screwed shut, soft moans beginning to leave his throat with every outward breath. Senku was so perfect. His little noises, the warmth inside him. He'd feel even better without the condom, but it was better this way. He'd look into other modes of contraception that would allow him to feel skin on skin. For now, though, it was just enough. Buried into his sweet, small assistant, Senku mewling against him. 

It didn't take long until Xeno could feel himself getting lost to it. That was  _ no good _ \- he couldn't cum first, he needed to feel Senku's walls spasm around him, he had been dreaming about it for a good while, now. He slowed his speed for a moment, a hand reaching down now to rub his thumb against Senku's clit. There was no time wasted in slowly rubbing or teasing, Xeno instead feverishly massaging the swollen mound as his hips once again resumed it's fast paced rhythm.

Senku kept his hand over his mouth to muffle his noises just a little bit, not wanting the neighbors to become suspicious. Besides, Xeno could likely hear all of his gasps and moans just fine. 

Something made this feel... strangely better than Senku had felt in the past. Perhaps it was the reduced pain, or the alcohol still in his system, but he found his pre-orgasm tension making itself known much sooner. He didn't have the time to warn Xeno before he was coming, biting down on his hand to keep his noise down.

Senku’s orgasm came in such  _ beautiful  _ waves. A few quick and small clenches from Senku's walls, until suddenly his entire body wrapped and tightened around Xeno's cock. He had to pause, just for a moment, the motion of it all nearly sucking Xeno in deep and keeping him rooted. A shaky moan left him, nails digging deep into Senku's thighs. He needed to go, he needed to move  _ more _ , waiting until Senku's orgasm finally calmed before he resumed his rough thrusts. 

It did not take long, just feeling Senku's orgasm already pushing Xeno towards his peak. A few good, deep thrusts, and Xeno was letting out a moan of his own, much less shy than Senku, for a moment forgetting entirely that they were not the only two in the room. He stayed deep, hips jerking on their own as his orgasm rocked through him, the condom feeling all too hot around his length. 

Xeno was left panting, doing his best to regulate his breathing, never actually removing himself from Senku's body. Not yet. Not until he absolutely needed to. Xeno looked down to Senku, taking in how he looked, so flushed and out of it, eyes half lidded with their corners filled with small tears. "Ah..." Xeno cooed softly, gently taking Senku's hand into his own, thumb running over the bite mark the boy had made. "Poor thing - this will definitely bruise..." Xeno's eyes closed as he placed a small kiss upon the bite mark, "if you wished to be bit so bad, you could have asked me."

Senku could feel his entire body shaking as he came down from his high, his eyes gently closed and mouth slightly open as he tried to regain his breath. He barely registered Xeno's words, just enough to mumble something about trying to keep quiet.

A chuckle fell from Xeno. It seemed that Senku was too far gone, both to the alcohol but also his own exhaustion, to properly respond to such a comment. "I suppose it's time to get you to bed". 

Xeno's arms wrapped tight around Senku, preparing himself to pick the boy up. He wouldn't have to take him too far, and Senku was much smaller now. He stood then, encouraging Senku's legs to wrap around his waist, not yet exiting his body but growing more flaccid now which definitely made it hard to stay rooted. "Well," he said, not looking Stanley's way as he turned from the living room. "I'll see you in the morning, Stanley." 

"Wait-"

Xeno could hear his friend shuffling, and Xeno couldn't help but hold a smirk as he carried Senku away. 

"You're not serious-... You  _ are, _ oh my God." 

Xeno did not look back at all, focused only on carrying Senku, soon entering his bedroom door. He soon leaned over the bed, his cock now finally falling from Senku's body, allowing him to remove the condom and properly toss it away in a nearby trash bin. He did not leave Senku alone, however, crawling right into the bed after him, bringing his body close to the boy as he tugged covers around them both. Senku's body was still awake, though definitely limp. It reminded Xeno of the first night he had Senku in his bed... though, the alcohol was far from effective as the drug. 

Xeno chuckled softly as he ran his fingers across Senku's face, clearing the hair from laying in front of his eyes. "I have a feeling I may be in trouble, come tomorrow morning. From both of my current roommates."

Senku whined when he was picked up and set down again, but his eyes remained closed until he felt the weight beside him and the gentle hands on his face. He grunted in response, snuggling up closer under the blankets. Xeno had neglected to dress him again, and the rapidly cooling sheen of sweat had Senku freezing.

Senku's body was showing small shivers. Xeno wrapped his body even further around the boy, now rubbing at his back and hips. "Are you cold?" he asked, his voice a slow hum. He laid kisses against Senku's forehead, being sure that the covers had him covered completely. "You did amazing tonight. You really did a good job teasing him." It was, in reality, more Xeno that did most of the work in pissing Stanley off. Senku was along for the ride, willing only because the alcohol caused him to give up the fight. Xeno only hoped that Senku wouldn't be too upset in the morning. 

Xeno gave Senku one last kiss - this one on his lips, slow and innocent. "Sleep, my dear," he said, closing his own eyes, "hopefully your body does not make you too sick in the morning."


	9. Experiment 09

Senku didn't need Xeno's permission to sleep, he was only halfway conscious for the affection anyway. He had no dreams, but he probably would've preferred it that way.

When he finally woke up, it was to a stabbing pain in his head, and a stirring in his stomach. It took all his strength to get up and drag himself to the bathroom, not caring at the moment for his undressed state. All he needed was to unload his sick into the toilet, clothes could come later.

The rocking of the bed was enough for Xeno to wake. At first, he had only thought Senku had slipped away to use the bathroom. But the sounds that came were far from as simple. Xeno took a deep breath, bringing himself from the bed, fixing his clothes for a quick moment before heading out into the main room of the apartment. Stanley was already awake, but Xeno paid him no mind, heading to the kitchen. 

Stanley, however, did mind, coming up behind Xeno as he fetched a bottle of water from the fridge. 

"Your little toy seems to be sick." Stanley said, his voice dripping with a bit of venom. 

Xeno held back a small smile, "please do mind your words. And yes, I know," he reached into one of the cabinets, fetching the bottle of painkillers, "I'm working on it." Xeno turned then, flashing a courteous grin to his friend, "don't act as if you didn't also have fun."

Before Stanley could properly answer, Xeno turned from the kitchen and towards the bathroom. Senku never did fully shut the door, but Xeno still waited until he heard the sink running to pop himself inside, placing the painkillers and water bottle onto the bathroom counter. "It will help. We will also need to get some light food into your stomach, when you feel you can handle it."

Senku could only muster a weak glare at Xeno, but gratefully took the painkillers and water. It would help a lot. "If I had known it'd feel like this, I wouldn't have drank anything..."

"Your body does not match your mind, it seems your tolerance is a lot lower than we could have guessed. Perhaps only one shot, next time?" Senku didn't need to know that it was, in truth,  _ three  _ that had him feeling like that. "Come, then. Back to bed - I'll keep the lights dim for you. Most of your morning will be spent resting, but it will pass."

Senku nodded slowly, shakily grabbing a towel to cover himself before heading back to the bedroom. He quickly grabbed a pair of underwear and a shirt and dressed himself before going back to bed.

Xeno did not follow Senku back to the room, not at first. He did make sure to bring the boy his phone, seeing as he left it out in the living room the night before, but other than that he let Senku rest. He was not giving any immediate signs that he remembered the night before, but Xeno had presumed he was not drunk enough to enter the stage of forgetting your actions. 

Eventually, Xeno came back into the room with a can of ginger ale as well as some plain crackers. He placed both of them on the side table, sitting on the side of the bed, "are you feeling any better?" He needed to ask... he needed to know if the events of last night were all for naught. "Do you remember... anything from last night?"

Senku carefully sat up to inspect the can, pleased that it wasn't open, before opening it to take a sip. "...I do. And if I didn't, I think waking up naked and sore would give me a hint..."

Xeno let out a soft hum. There was a small bit of animosity in Senku's voice, but it was far from as angry as he would have been a few weeks prior. He watched Senku slowly take a sip, a smile curling on his lips, "I see I was right, as well. You bit your hand enough to bruise."

"I don't care, better than the neighbors asking any questions." Senku mumbled, setting the can down before grabbing a cracker. "I've got enough bruises anyway, one more doesn't make a difference."

"Hmm, I suppose," Xeno took the time to look more down at Senku's body. His clothing did not show off all the marks that Stanley had made the night before, but a few hickeys could be seen just above Senku's neckline. "For the next couple days it would be wise to not leave the apartment, or at least wear a shirt with a higher neck."

Xeno stood then, walking closer to Senku, soon leaning town as he tilted the boy's chin and forcing Senku to stare up at him. Xeno left a small, chaste kiss on Senku's cheek, staying close as he whispered out, "I am happy to see you are feeling a little better. You should come out, soon. Stanley will be leaving soon. You can give him more dirty looks before he leaves."

Senku rolled his eyes, pushing Xeno away, though whether his push was weak on purpose or due to circumstance wasn't exactly clear. "Sure, sure. I will in a little bit..."

Xeno only smiled warmly, letting Senku push him away. "Whenever you are ready, then." Though, of course, Xeno could not pass up the chance to place a small kiss on the hand that had pushed him away. There was nothing stopping Xeno from being overly affectionate, now. Senku was going to have to get used to it. 

He left then, even if he was eager to stay and tease the boy more. There was still work to be done, though Xeno took to doing most of it at the dining room table as he listened to his friend talk about his plans. Stanley had only been staying for a short time, already needing to head back out. It made it easy to stay at Xeno's for the few days, not bothering with hotels. Occasionally Stanley's voice would drop low, talking to Xeno with whispers and hand motions. Things that made Xeno's cheeks feel hot, and a slight grin appear on his lips.

He wished he could have seen Stanley totally ravish Senku. The way Stanley described his noises sounded adorably pathetic.

Senku emerged a while later, eyelids low as he brought out the empty can of ginger ale to toss it in the recycling. He ignored the two older men at the table, instead moving to make himself a cup of coffee.

The second Senku showed his face, Stanley immediately stopped talking, clearing his throat into his fist. It made it dreadfully obvious they were talking about him, though Xeno only hoped that Senku did not hear the contents of their words. 

"I actually have to head out," Stanley said then, standing from the table and walking around towards the kitchen counters. He was quick in his actions, his arm wrapping around Senku's shoulders, "I'm sure we'll meet again in the future, kid." Before Senku could properly react to his movements, Stanley leaned down and grabbed at Senku's chin, only to keep him in place as he quickly engulfed the boy's lips in a kiss. It was not too long - and Stanley knew better than to put his tongue anywhere close to the boy's teeth. 

Breaking, Stanley showed a large grin, letting go of Senku entirely, "I'll be missing you, maybe."

Senku tensed up at the kiss, a disgusted look creeping onto his face as he glared up at Stanley. He scoffed, quickly turning back to the coffee pot. "And I won't miss you at all." He punctuated his cutting remark with a light kick to Stanley's shin, and another glare.

Stanley moved back - only giving the smallest wince, his grin growing wider and toothier. "Yeah, probably not!" With his hands on his hips, Stanley leaned down once more, dangerously close to Senku's face, knowing full well the kid would back up, "but you  _ will  _ think of me a lot, won't you?" 

Taking a few steps backwards first, Stanley soon turned with a small wave to his hand, "I'll text you when I get to my next destination, Xeno." 

"I know you will." Xeno said over his cup of coffee. 

Stanley then grabbed his bag, saying no other words as he left the apartment, the door soon clicking behind him. 

With a soft sigh, Xeno placed his coffee down. "He visits two times a year or so, so you won't need to worry much. I'll be sure to warn you next time, though," Xeno began to wear a grin of his own, "I suppose, by that time, you may have your old body back." Something in Xeno's tone suggested that would most likely not be the case. It would take a while to understand this serum, after all.

"I'd better." Senku mumbled, quickly turning back to the coffee pot and filling his mug. Though for some reason, it didn't sound so bad... he'd just have to push down that thought, he needed to get back to his normal self.

"...so, now that Stanley's gone, what's the plan for today?"

"Hmm, well," Xeno slowly closed his laptop - the rest of his work could be done in his actual office. "Same as yesterday, for the most part. I am sure you have some school work, and afterwards you can join me for the usual routine. After that, well." Xeno stood then, grabbing both his laptop as well as his cup of coffee, "we can also have a repeat of yesterday, though I think you should stray from alcohol for now." With a knowing smirk, Xeno walked from the kitchen and into his office.

Senku stared after Xeno, a blush forming on his face as he mumbled "You wish" at the man's back. At least he wasn't as sore this morning, but he didn't want to get fucked a third day in a row, did he? 

To keep any sort of questioning thoughts at bay, Senku instead grabbed his laptop, ready to finish his classwork for the day.

* * *

The day, much as the day prior, passed quickly. Xeno busied himself in his work, eventually finding Senku joining him near mid-day. He gave the boy the usual tasks, and aside from the occasional chatter about work and the current projects going on at NASA, everything felt mostly normal. There was still a bit of an awkward tone in Senku's voice, one that Xeno would match with his more conniving tone. They both knew what happened last night. And they were both aware that the night ahead could have a possible repeat. Xeno only hoped that Senku would not back out. 

With work finished, Xeno set out to tidy the house, Stanley's arrival having made the place more unkempt than usual. Stanley wasn't exactly the best at picking up after himself. But, eventually, the living room was back to it's spotless self, as well as the kitchen. Xeno even made sure to put the box of... _ 'items'  _ away in his room, even putting the lube and condoms into his bedside table, for safekeeping. 

That evening, neither Senku nor Xeno bothered much with movies, instead putting on a simple documentary while the both of them busied themselves in their own hobbies and studies. It was not long before the sun light stopped filling the apartment windows, and Xeno felt the creeping urge to rest his eyes fill him. 

Of course, he had no intention in simply going to lay down and sleep. 

Xeno put away the book he had been reading, walking around to the back of the couch, standing behind his assistant who happily seemed distracted by his game system. Xeno leaned over, watching the game play by, his hands resting and gripping on to Senku's shoulders. "It's bedtime," he hummed out, lips close to Senku's ears. "The choice is yours - but I am sure you've learned these past few nights that my bed is much more comfortable than the couch." A hand slowly moved upward, gently poking at Senku's chin and making his neck tilt, allowing his lips to then trail down the boy's neck. "Won't you join me, Senku?"

Senku tensed under Xeno's touch, a light blush spreading over his cheeks. "F-fine, but... only because the couch is bad for my back." He huffed, trying to ignore the lips ghosting over his skin as he saved his game.

Xeno chuckled against Senku's skin, soon pulling away. "Of course, your comfort is most important, after all." Xeno turned then, walking to his bedroom and allowing Senku to take his time in following. He busied himself with changing from his more casual wear to a night time wear - only boxers as well as a t-shirt. As he sat on the bed, he sent a smile to the young boy entering his room. "You seemed to have been in higher spirits today, without Stanley around. I'm happy to see you back to normal. Or, well. Mostly normal."

Senku had waited a few minutes for Xeno to get changed before coming into the room, not particularly wanting to see the man undress. He brought in his phone and console, setting them down on 'his' side of the bed before grabbing a new pair of underwear, his pajama pants, and a t-shirt, which he brought into the bathroom to change.

Xeno began to slowly arch an eyebrow - so Senku still didn't feel comfortable changing in front of him? Such a pity. Xeno wasn't going to do anything while he was changing, but, thinking back, the last time Senku had changed in front of him ended more in Xeno's favor than in Senku's... 

Oh well - it was no matter. Xeno put himself properly into bed, his back laying against a few pillows and the headboard. His phone chimed a few times on the nearby side table, Xeno letting his attention fall to the phone and not his changing assistant in the next room over. It was only a simple text - Stanley had made it to his next destination. He'd be off for a few months as usual, though Xeno had no clue on when his next visit would be... it excited Xeno to think about how much Senku may change by that time.

Senku came back in once he was dressed, stretching out with a yawn before he climbed into bed. He immediately turned on his console and plugged in his headphones, planning on ignoring Xeno for the rest of the night.

_ Ah _ \- so he was going to make this hard. Xeno should have expected that. 

With a soft sigh, Xeno placed his phone down on the bed. He could let Senku have his moment. Ignore everything. But that risked everything falling back into normalcy. Xeno had worked too hard for Senku to just brush everything off. So he shuffled slowly across the bed, leaning over Senku's frame as he gently tugged one of the headphones from the boy's ears, speaking low. "Senku? We have some things to discuss."

Senku narrowed his eyes, glancing over at Xeno, before sighing and pausing his game. "What? We can't discuss it tomorrow?"

"Hmmm,  _ no, _ " Xeno only moved closer, his arm wrapping around Senku's body as it soon sat on the bed beside him, Xeno's weight leaning on it as he pressed the game into the bed. "It's best we talk about it now, while the memories are still fresh. I want to know... how much you  _ really  _ remember from last night."

Senku tensed under Xeno's touch, his cheeks tinted a light pink. "Um... most of what I remember was of the movie, but... I-I just remember feelings. Not the exact scenarios."

Xeno hummed softly, his disappointment clearly reading on his face. "That's a bit of a pity..." Xeno's hand then moved with caution, watching Senku's reactions carefully as he grazed Senku's cheek with the pad of his thumb, feeling the heat of the boy's blush beneath his skin. "I could tell you, if you wish." 

It didn't fully matter what Senku's answer would be, Xeno continued anyway. "You got drunk - perhaps a little  _ too  _ drunk. You crawled right on to my lap, begging to be put into bed." A mild lie - Xeno  _ did  _ lift him there, "I wished to watch the rest of the movie, but your soft whines and the swaying of your hips as you tried to get comfy... well..." Xeno gave a small shrug, "you were so accepting of my wandering hands, of course due to the alcohol. I suppose, given that, your little whines and confessions on how good it felt couldn't really be taken as pure consent, but I couldn't help myself. You were finally so... _ eager. _ " 

"Even now, Senku," Xeno's hand left Senku's cheek to now ghost his fingers across the boy's shoulders, "you are so tense, trying to hide your body from me. Do you believe I'd hurt you?"

Senku tried to tune out the recap of the night before. "I... I don't think you're going to hurt me, but..." He squirmed under Xeno's touch, unsure what to say next. "I just still... I'm not sure if I'm okay with it."

"You seemed quite sure last night. They say that alcohol brings out one's true self. Some become angry, or depressed. And you," Xeno let out a small chortle, "became clingy, and would clench so beautifully every time I reminded you that Stanley's eyes couldn't leave your body."

"You even," Xeno's once gentle smile soon twisted a bit at the sides, "if my memory serves right, called me  _ daddy  _ a few times."

Senku's cheeks were bright red now, and he turned his face away from Xeno. "Sh-shut up..." Something stirred in his stomach, though, at the mention of the nickname. Of course he wouldn't say that, it was disgusting...

The retort only brought Xeno back to his more gentle state, a soft sigh leaving him as his hand went back to Senku's cheek, now cupping it. "Senku," he began, tone just as soft as his touch, "If it settles your mind at all, I have... always thought about having you in the same bed as me, just like this. My cute, high energy assistant who was never afraid to tell his superior scientists when they were wrong." Xeno leaned forward then, his lips pressed against Senku's forehead, "the change in your body and your size do bring new things to the table, but they are not the driving force in my desire to pleasure you." 

The kiss on Senku's forehead slowly traveled lower, Xeno soon kissing at the boy's temples and soon at his cheeks, "I like you, Senku. I have for quite some time." Lower now - Xeno's lips falling against Senku's jawline. "Allow me to prove that to you."

Senku tensed and squirmed under the gentle touches, and as much as he wanted to be disgusted and push Xeno away, he couldn't find the strength within himself. He glanced up, meeting Xeno's eyes for a moment, before sighing. "F-fine..."

Xeno's kisses turned into a smile. Senku was far from giving in fully, but it was a start. The previous night had definitely done its job in tearing down a few walls. Xeno reached for Senku's game system, placing it safely on a nearby side table. No need for it to get thrown from the bed. 

Afterward, Xeno turned his full attention to Senku, now shuffling and adjusting himself on the bed to straddle the boy's small body, both of his hands holding either side of Senku's jawline as he kissed between his eyes. "Tell me, Senku, do you remember sharing a kiss with me last night?"

Senku pursed his lips, still tense and making some attempts to cover himself, but slowly shook his head. "I... n-no."

Xeno could sense the way Senku tensed, the hands cupping his cheeks soon slowly rubbing at his cheeks and jawline. "There's no need for that. I've told you already, I have no intentions on hurting you." His head dropped lower, eyes closing as his lips just barely brushed against Senku's, "I will go as slow as you need me to, the entire night if necessary." He closed the distance then, the kiss staying simple and innocent... for _ now. _

Senku relaxed a little as his lips met Xeno's, happy with the gentleness, the borderline-sweetness. He was still unsure, but... at least for now, it was... nice.

Xeno could not keep his kiss so pure for too long, of course. As soon as Senku began to finally calm his body, Xeno moved forward slowly. First he took Senku's bottom lip into his own, suckling on it, nibbling softly until the softest of heavy breaths fell from Senku's mouth. Xeno took it as his sign to enter, the kiss quickly becoming more heated, a hand sinking to the back of Senku's neck to pull him deeper into it. His tongue happily ran across Senku's, tasting the mint of his recently brushed teeth, taking his time in exploring his assistant's mouth. 

His hands did not stay pure, either, Xeno's free hand now running down Senku's torso. For a moment he could feel how Senku tensed once more, Xeno pausing to rub softly at his hips and stomach before Senku relaxed once more. Xeno then pressed his fingers beneath Senku's pajama top, fingers ghosting at his flushed skin before finally falling on a nipple, two fingers pinching and tweaking at the soft mound.

Senku let out a soft whimper into the kiss, his skin heating up everywhere Xeno touched. It surprisingly still felt good, the gentle touches over his skin, the light pinches and prods. He shuddered, his back arching to press his chest into Xeno's hand.

Xeno couldn't help but smile in the kiss, breaking apart for only a moment to speak against Senku's lips, "there we are... it all feels nice, doesn't it? No shame in that...'' Xeno wanted to continue the kiss, to drink in every single noise Senku made, but instead he slowly pulled away as his face moved down Senku's body. "I can make it even better for you," Xeno purred, pushing up Senku's shirt until both of his nipples showed, one more perky and teased than the other. Xeno continued to tease that one with his fingers, soon slowly circling the other with small pecks before finally taking the mound into his mouth. 

He teased it with everything he could think of. Suckling, flicking his tongue against it, slight nibbles and tugs with his teeth. It did not take long until that nipple, too, stood erect and swollen. The sight caused Xeno's breath to feel heavier than before. With a lick to his lips, he grabbed at the hem of Senku's shirt, slowly pulling the entire thing from his body, soon covering Senku's body instead with his wandering hands and tongue, touching every bit of him that he could.

Senku whimpered and moaned softly under Xeno's ministrations, his eyes soon fluttering shut and his lips parting with each puff of breath. He really shouldn't be feeling this good, but it was the same as what he felt last night. So warm, so gentle... there wasn't a reason to fight it just yet.

Xeno separated from Senku's chest only for a quick moment, lifting his own shirt up and over his head, letting it fall to the floor. He was entirely clothed every single time he touched Senku before, but this time they needed to be on more equal footing. Xeno continued to leave small bites at Senku's nipple, soon letting those bites trail up his neck, soon taking Senku's hands into his own. "You can touch, too," he whispered out, placing Senku's hands onto his shoulders. "Touch me, pull my hair, scratch me, whatever it is you want." 

Xeno's hands fell back to Senku's body then, both of them so big compared to his small size. He trailed them down his torso and hips, hooking into the boy's bottoms and underwear. He slid them off slowly, taking time to let his fingers graze his skin the entire way, before letting the garments fall with the others. He did not pay any attention to Senku's sex - not yet, instead letting his hands grip at the boy's hips as he began to cover Stanley's old hickeys and bite marks with ones of his own.

Senku let out a soft whimper with each press to the bruises that dotted his skin, a dull pain spreading from each one. His own hands found a place on Xeno's shoulders, ready to move or push or scratch if required.

" _ Senku, _ " Xeno whispered out the name against Senku's neck, kissing at the new marks he had made. A few were a bit high, but they were his marks now. He'd never let Stanley know how much jealousy the markings had caused. Senku would need a turtleneck for a few days, or else the neighbors were going to start asking a lot of questions. 

Xeno wanted to stay latched to Senku's neck, but he needed to pull away, soon sitting on his knees. He did not show much hesitation as he pushed down his boxers, not at all shy to show off exactly how much Senku has affected him already. Xeno shuffled slowly on the bed, allowing him to fully remove his boxers, before pulling at Senku's legs to widen them. It allowed room for Xeno to move close once again, though he stayed sitting up, looking down to Senku as he slowly rubbed at the boy's legs and thighs. 

"Do you see, Senku?" Xeno took his cock into his hands, pressing it down against Senku's stomach, nearly reaching his belly button in length. "What it is that you do to me?"

Senku's eyes widened, his face tinted bright red as he stared at Xeno's cock. How did he fit that last night? He glanced back up at Xeno, before pushing back against him. "P-protection, remember?"

Xeno hummed softly at Senku's feeble attempts to push him away. "Of course," Xeno's eyes closed as he leaned forward, his weight easily able to win against Senku's pushes as he laid a single chaste kiss to his lips. "I have no intentions on impregnating you, or causing you to take that medication again." Xeno left Senku's lips only to reach over into the nearby table, the drawer holding the lube as well as the pack of condoms. Xeno grabbed both of them, presenting them to Senku, "We can look into more concrete methods of birth control once we know for sure if you will have a monthly cycle." 

Xeno looked up then into Senku's unsure eyes, lips still straight and shoulders tense. With a smile and a sigh, Xeno put the items down on the bed. "Senku, you seem to keep forgetting." His hands then cupped at Senku's cheeks, leaning down to place a kiss to the tip of his nose. "I intend to make you feel good. I need you to trust me." Xeno nearly asked if he had ever given Senku the impression that he couldn't be trusted... but Xeno was able to catch himself before actually saying it, knowing full well the boy would have a  _ number  _ of accounts. Instead, Xeno pushed his forehead against Senku's, hands softly running through the boy's hair. "Just relax. Allow yourself to feel good."

Senku stared up into Xeno's eyes, his own were wide, glassy and unsure. Finally he sighed and nodded, "I... I can  _ try, _ I guess." He looked away for a moment before glancing back. "Promise it won't hurt?"

Xeno's smile widened, though his eyebrows began to furrow. "Oh, Senku....  _ no, _ I cannot promise that." One of Xeno's hands left Senku's hair to then graze it's fingertips down his slender body, Xeno's eyes watching his hand move further down. "You are very small, and there is always the chance of a bit of pain. I don't wish to lie to you.”

"However," Xeno's eyes shot back up to Senku's, just as his hand began to creep between Senku's legs, sliding against his slit, "I can promise you that if you tell me you are in pain, we will stop until you are comfortable. Is that satisfactory?"

Senku's breath hitched, his lips pressing together at the gentle attention paid to his sex, but he nodded. "F-fine..." He finally laid his head back against the pillows, his glare softening ever so slightly.

" _ Good boy, _ " Xeno purred out now, catching Senku's small pout in another kiss, no longer attempting to keep things pure or simple. His tongue forced passed Senku's lips, running against Senku's more timid tongue as his fingers finally slipped between Senku's folds. He was not quite wet enough to easily slip into his sex, so instead Xeno happily focused his attention on Senku's clit, finger pads softly massaging the mound in a circular pattern. As soon as Xeno could hear the soft mewls already leaving Senku's mouth, he quickened his pace. Clitoral pleasure was one thing Senku was getting more comfortable with, that much was certain. It didn't even take too long before Senku's hips were wiggling against the touch, his sex soon flowing with juices. 

Xeno's fingers slid lower then, catching the fluids and running them all along Senku's folds. He broke the kiss only to hum out "you're already _ soaked. _ You don't need to tell me how good it feels, though I would love to hear it from your lips." Xeno was gentle, though he started with two fingers, sliding them into Senku's entrance with ease. He did not wait to start a slow pace, being sure to curl and scissor his fingers when he could.

Senku felt a bit better about releasing quiet moans, his hips canting up ever so slightly to meet Xeno's fingers. His eyes would flutter closed and open, and his hands traveled from Xeno's shoulders to his back. "F-fuck, it's good... i-it's good...~"

Hearing Senku's voice, not just moaning but  _ speaking  _ like that. It was so much different from their first time in the NASA offices when Senku was trying so hard to muffle every noise, or every single other time when Senku absolutely refused to acknowledge the pleasure he was feeling. Even the previous night Senku had only been giving out small mewls of confused excitement, all mixed with worry of Stanley watching so closely. 

But now, Senku's voice was falling from his lips, admitting the truth to them both. Xeno felt a surge of pride, capturing Senku's lips once more. He wanted to hear him talk more, hear him scream out, but his lips were all too tempting. Just as the night before, Xeno desperately grabbed for the condom box, shaking out a single packet. Though, unlike last night, Xeno's mouth was currently busy and unable to rip the rubber from its casing. His other hand left Senku's heat, only to aid in opening the condom package, wasting not a single second as he rolled it on to his cock. The condoms came pre-lubed, but that did not mean it wouldn't hurt to add a bit more, Xeno making sure that his cock was coated in lubrication before he pressed the tip of his cock into Senku's clit. He played with it there, enticing a moan from the both of them, but eventually broke the kiss as he rocked their foreheads together once again. "Senku," Xeno breathed out, eyes dark and half lidded, his hand now coaxing his cock to press against the boy's entrance. "Try not to hold your breath..." 

With a gentle push of both his hand and his hips, Xeno slid deep into Senku's body. Slowly, almost agonizingly slow, but Xeno watched Senku's face for any signs of pain.

Senku made himself take deep, shaky breaths as Xeno entered him. The stretch was uncomfortable, but not painful, and even had an undertone of pleasure to it. For the third time in the last few days he felt  _ full, _ and there was something so disgustingly satisfying about it.

He let out a soft moan, watery eyes fluttering shut at the sensation.

As Senku's eyes closed, small tears escaped and fell down into his hairline. Xeno did his best to kiss the trail of those tears, petting back Senku's hair, rooting himself deep into Senku's body but not yet moving. Instead, he waited, softly kissing along Senku's cheeks and jawline, all until Senku's breathing finally regulated. Xeno took it as silent approval to continue, bringing his hips back before shoving himself back in, this time faster than before.  _ Once more _ \- even faster, all gradually growing until Xeno found himself at a moderate and even pace.

Senku let out sweet gasps and moans each time he felt Xeno's cock thrust home. He was the perfect size, tip just kissing Senku's inner barrier, drawing out more whines as his steady pace continued.

Xeno left kisses along Senku's face until he met with his lips again. He could not kiss fully - not now, when they were both breathing hard. Even so, Xeno desired to drink in every single moan that Senku let escape. He was not under any influence here. No drugs. No alcohol. Not even half asleep or trying to quiet himself in public. Every single noise was his own, and Xeno needed more. 

His fingers began to slide against Senku's clit, rubbing motions matching the rhythm of his thrusts. " _ Senku, _ " he purred out the boy's name once more, never getting tired of how it felt on his lips. "I need you... to scream for me, tell me exactly how it feels." His lips caught Senku's between his words, a soft moan of his own soon falling into Senku's mouth, "just like before, at NASA. Describe it to me, in detail."

Senku's lower lip quivered as he looked back up at Xeno, his hips never ceasing their languid movements. "I... mnn... I d-don't know if I c-can..." He leaned his head back against the pillows, letting out another gasp. "J-jus'... feels _ good _ ..."

A grin grew on Xeno's lips, his tongue quickly licking at them. Such delicious little sounds. He took the chance of Senku's tilted head, letting his teeth run against the boy's jugular. Xeno could feel the outline of Senku's small Adam's apple - so he  _ still  _ had that part of him despite the extensive change. Xeno really needed to do a full extensive study on Senku's testosterone and estrogen levels. But such a study could come later. For now, Xeno was only focused on driving more noises from the boy, his thrusts occasionally turning slow and deep before resuming a much faster speed. 

"What feels good?" Xeno finally asked, his bites now covering Senku's collarbone. His hand never left Senku's clit, now matching his more wild and strong pace. "Say it, Senku... tell me how good it feels... to have me  _ fucking  _ you."

"F-feels so good w-when..." Senku paused, letting out a soft whine. "Whan you  _ f-fuck me-e...~ _ " His eyes were still watering, and he chewed at his lower lip. It was humiliating to admit, but he couldn't bring himself to care right now.

Xeno's eyes closed as he listened to Senku's soft mewls and lewd words. It caused a warm shiver to run down Xeno's spine - just hearing Senku say such words was enough to push him far over his peak. But he held back with gentle pants of his own, moving back up to catch Senku's lips once more in a breathy kiss. "You are.... such a good boy, Senku..." 

Xeno's free hand fell deep into Senku's hair, gripping, his nose soon nuzzling at the boy's temple as his own moans began to leave his chest. He was close, he could feel that, but the idea of coming before Senku's body clenched and climaxed around him still seemed like such a waste. Through his pants, Xeno softly moaned into Senku's ear, "I need you... to come for me, Senku... let me feel it." It was a gamble on his own endurance, but Xeno brought himself up to the highest speed his hips could manage, a loud smacking noise reverberating throughout the room, his fingers never once ceasing it's constant torment to Senku's clit.

Senku let out another high-pitched whine, his nails digging into the skin of Xeno's back. He felt every muscle in his body tense, finally letting out a moan as he finally reached his release. His mouth hung open, tongue lolling from between his hips and his eyes glazed.

That was all it took - the mix of Senku letting out an authentic moan, one the neighbors must have heard. The clenching, his face, so lost to pleasure, tongue hanging out in such a tempting way that Xeno had to run his own against it. Xeno continued his pounding as Senku's body clamped down on his cock, gripping tighter at Senku's hair as his own peak finally crashed down onto him. Xeno tried to grit his teeth but it did nothing to hold back his own moans, brows furrowed as he rocked his hips slow and deep, filling the condom and making Senku's body feel even hotter. 

With heavy pants, Xeno placed his forehead against Senku's, not yet wanting to leave him. Through the fog of his mind, Xeno littered Senku's face with gentle kisses. He stayed until he felt his cock begin to soften, knowing it was best to remove himself now and prevent risk of anything escaping the condom. So he slid from the boy, slowly, being sure to give Senku's legs a few soft pets as if to praise him for a job well done. Standing from the bed for only a moment, Xeno properly tossed the condom in the nearby trash bin, quickly coming back to lay beside Senku. 

The boy was still panting softly, Xeno now running his fingers across the boy's soft cheeks. "You did amazing, my boy..." Xeno hummed lowly then, situating himself comfortably in the pillows, "perhaps... next time, I can convince you to ride me."

Senku opened his mouth to protest, that no he wouldn't be riding Xeno, but... it almost felt like a lie to say that. 

"W-whatever..." He mumbled, though he cuddled closer to Xeno, hiding his face in the pillow. "'M cold..."

Xeno only chuckled at Senku's movements, grabbing at the blankets now as he surrounded them both with the soft fabric. "You're almost acting like a child with that mumbling," Xeno said, his tone like that of a scolding parent, though his amusement shined through. He made sure to tuck Senku in fully, soon even daring to wrap his arms around Senku's frame, tugging the boy closer to him. 

Xeno's thumb rubbed softly at Senku's shoulders, his eyes closing as he hummed softly to himself. "Things will begin to fall into alignment, now. Our free time can go to conducting more research on the serum. You'll be having a break coming soon in your schooling, I believe," Xeno nodded to his own words, "Yes, I can take some time off as well, we can use that time to properly crack down and see if we can recreate the serum..." Xeno's mind began to wonder how they would check the effects. Rats, perhaps? Ethics and morals always came into play when dealing with animal testing, but if his calculations were all correct, the serum should work on mammals in general, with no harm done. And human testing always came with way too many guidelines...

Senku nodded slowly, "Yeah, winter break is coming up, it's only a couple weeks, but..." He paused, brows furrowing. " _ Shit _ ... my dad is flying over for Christmas." He stared up at Xeno, eyes wide. "How are we gonna explain this to him?"

Xeno nodded along slowly, a couple of weeks would be more than enough time to get a good start on recreating the drug... 

But Senku's words caused him to pause, brows furrowing as he held a smile - this was...  _ unexpected. _ Xeno knew of Byakuya. Senku's father was one of the major reasons the young boy got such an easy internship with NASA in the first place, seeing as his father had been a part of the company for a few years and showered NASA with recommendation letters. He was a good father. A doting father. 

A father that would most likely, and understandably, freak out when he learned his son had gone through such a wild body change. Senku may have been able to sweep the drugged coffees and drinks to the side (for now), but Byakuya would be a different hurdle altogether. 

"Right..." Xeno began, his tone calm as he took a deep breath. "We... only need to tell him what he needs to know. You underwent an experiment, and your age regressed a small handful of years. He does not need to know of your more...  _ personal  _ changes. And..." His hands softly held Senku's cheeks then, giving the boy a warm smile as he placed a single kiss to his lips. "He does not need to know of our relationship." 

Relationship...? Was that something to call this? Xeno wasn't fully sure what he could call Senku just yet, given his outward appearance. But it was a sort of relationship that would anger a loving father, for sure.

".. _.relationship? _ " Senku pouted as he thought, "I don't think I would call it that, personally..." He still wasn't too pleased with the arrangement, but he didn't want to upset Xeno at this point. "But I agree, we should only tell him what he needs to know. He'll probably be upset enough without delving into personal matters."

Xeno chuckled softly at Senku's small pout. So he focused on that part, too. Tilting his chin with a delicate touch, Xeno laid another small kiss to Senku's lips. "Do you not like that? Even if it does not have a proper label, we do have some sort of relationship going on," Xeno gave another kiss, a laugh falling into it, "I suppose we'll just have to be sure that you don't call me  _ daddy  _ while your father is around." The thought shouldn't have excited Xeno as much as it did. He was a little disappointed in himself that he didn't demand Senku to use the name tonight, but that only meant he would have to sprinkle it in more and more in the future.

"You'll be lucky if I call you that at all." Senku grimaced, poking Xeno's nose, before his face relaxed into a grumpy pout once more. "But... we can think about all that later. I'm too tired to deal with it right now..."

Once again - such a cute, childish gesture. Was this going to become more normal...? If so, Xeno could definitely get used to it. Not only that, but Senku did not outright deny the possibility of him using the name again... It caused Xeno's thoughts to stir wildly, but he did his best to quiet them for now. As Senku had said, it was simply too late to deal with such things at the moment. He would wait for the morning to bring it back up. 

"Then rest, for now," Xeno hummed out, his arms once again curling around Senku's frame to hold him close. "You've had some very,  _ very _ taxing days, recently" And, with the announcement of Byakuya's imminent arrival... it was about to become  _ a lot _ more stressful. 

For the both of them.

* * *

**Part I: END**

**Author's Note:**

> [Feel free to join the Kingdom of Shipping discord server!](https://discord.gg/zedJR9n)


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